You can put color filters on the background light to change its color, to make the background appear red or green, etc. Middle gray backgrounds are best for that, white or black are harder. White needs little filter power, but is only pastel color (more power burns out to be white), and other lights can wash it out. Black gives very saturated colors, but requires much power to light it. Middle tone gray is best and easiest. Keep the background distance well back (6 or 8 feet), no colored reflection on your subject.
Or adjusting the power on the background can substantially change its appearance.
You can make various shadow patterns too, to add interest. Just focus a smaller spot in the center (grid or snoot), maybe to halo the head, or to let the corners fall off (slight effect of this next below). Or put the light closer aimed across the background for a gradient, light to dark. You can place a intentional pattern of obstacles in front of light (a row of vertical bars maybe) to make interesting shadows.
This part is a Big Deal
All lights change their own color slightly with power level, whereas Flash White Balance is a simple constant, as if somehow one size fits all. Using the Raw White Balance Tool to click on a test shot White Balance Card, which neutralizes the white card color, which changes Flash White Balance to a Custom value that is actually correct this time. This Porta Brace White Balance card is less than $6 at B&H. It is 6x9 inches, plastic, durable and washable, accurate, inexpensive, and it works great. Or the Whibal white balance card $20 or $30, is possibly technically better, as they claim to test each card, and it costs a little more, and is slightly cooler than the Porta Brace. I have a couple of each, and I tend to use the Porta Brace cards, especially for portraits. My notion is that most of the other WB schemes are too complicated and too costly. This card method is direct to the point, simple and easy, is pretty much the definition of White Balance, and it works great. Just add the card to your first setup test shot (in the same light). Then you click it to tell the computer "This spot is neutral white, make it be neutral white" (qualified to a "color neutral" spot, below). Then anything in the same light will work out too, with the same correction. And we can easily apply this correction to all images in the session, with one click. More about that.
For portraits, get the dang camera out of Vivid or Landscape color profile. The ladies are always concerned that their hair comes out the right color. A Neutral color profile is appropriate for portraits.
The historical concept of White Balance was to manually shift the individual White Points of the three RGB histogram channels so that all three right ends of the data channels balanced, or all lined up, which forced pure white there, to match the presumed white content there. Photoshop Auto Levels does that. Today, the eyedropper WB tool causes the computer to shift the three RGB channels so all three have the same numeric value at this clicked spot - to remove any color cast there, on this known color-neutral value. So the card can be any neutral gray, including white (the definition of neutral gray is equal RGB components, with no color cast). In a pinch, we could use a piece of white printer paper, or it could be a white T-shirt or a white picket fence in the picture, perhaps a better try than nothing, but including an accurate known neutral-color source is the best way.
This time, the card is a bit blue in the first picture. All flash tubes vary their color with power level (just how life is), and White Balance adjustment is a major concern. This way makes it very easy, if you remember to do it (every session setup, it is NOT a one time thing). Don't place the white card close, where the bright light burns it out to 255, which would lose all it has to offer. An 18% gray card is pretty dark (close and more exposure is good for it), but there are newer light gray "digital" cards better suited for White Balance. But portraits should never be that glaringly bright anyway, and white bypasses trying to control printed gray ink colors. It is called White Balance, and a white card works great, but just don't overexpose it. It will be good to calibrate your monitor too - I use an old Sypder2Express, which seems great.
Thank you very much Erin, your help is greatly appreciated.
Don't overexpose portraits! If a shiny hot spot on nose or check, back off a bit. Skin tones are happy to back away from 255. Not dark, but not excessively bright. Brightest skin tone highlight here is under 240, and that is a good limit (230 to 240, IMO). Hitting right exposure simultaneously with the right white balance is the WOW! Try it slightly less bright once (judge it after being printed on paper by a really good printer).
A good tool: Overexposure clips the white end at 255. In Adobe Elements or Photoshop, moving the ACR Exposure slider (Adobe Camera Raw), or lowering Levels Tool (CTRL L) White Point, adjusts exposure results. Holding the ALT key (ALT in Windows - I think Option key on a Mac) while moving these slightly makes the image display go black, but then it shows the actual pixels which have been clipped. Same at black end if holding ALT while adjusting Raw Blacks or Levels Black Point. Purpose is so you can recognize WHERE you are clipping, on the nose or cheek or wherever. Shows WHICH pixels are being clipped. Don't clip skin tones. Hard to quantify, but less exposure than that is even better — Scenic landscapes may be a different deal, a little clipping sometimes improves their contrast, but in portraits, even a true white color probably should not be right on 255 - the face in portraits certainly should not be too close to clipping. Just look at results, and this tool helps to see. Certainly it is best if the exposure comes out close in the camera, but camera Raw allows a little tweaking later.
Move the camera viewfinder focus sensor up high in the portrait frame, to be on the subjects eye. A tripod really helps, no one here is going anywhere, and a flash sync cord is no issue on a tripod. Generally, a sync cord to the fill light (nearest to camera, which is also sort of aimed at the other lights), and then all the other lights triggered by optical slave sensors. These optical triggers work great in your studio or living room. All studio lights have them built in. Compared to the Commander TTL system which uses very low power signals, the optical slaves are triggered by final working power of the flash.
I move the PC sync cord to the Sekonic flash meter, and move the other end to each light, to meter each light individually. The incident meter must meter the light from the subjects position (next to their cheek or chin). The flash meter has a mode and button to trigger that cord and the flash on it, so it is metered. Turn off the other lights, and meter each light individually, to set its power level to be what you want it to be (yes, simple as that). I aim the flash meter directly at the light then, from very close to the subject (or background), in a consistent manner. Then to meter main and fill light together for the camera lens setting, I aim that meter at the camera, from under subjects chin. Then move sync cord back to camera, and to a near light, and have at it. Here is one description of that metering process. Background and hair lights do not affect camera setting or exposure (they only affect background and hair).
If you use tenth stop metering on the meter, you can easily compute the numbers in your head. How many stops from f/4.5 to f/8? Not easy (1 + 2/3 stop), but if we use tenth stop precision, then we easily know that (f/4 + 3/10 stop) to (f/8 + 0/10 stop) is 1.7 stops. On the camera, setting f/8 + 7/10 stop is simply two (third) clicks past f/8 (camera will show it as f/10). Only trick is that when beginning with tenth stops, remember that a meter reading of f/8 + 5/10 stop is NOT the same as f/8.5 (so f/8.5 may be halfway to f/9, but f/8 + 5/10 stop is halfway to f/11).
Of course, turn Auto ISO Off with flash in studio. Needs no explanation, but we are providing the light with flash, and we need no meddling.
Leaving the modeling lights on will keep the subject's eye pupil smaller, and should have no exposure effect on the exposure - but do use maximum shutter sync speed so this is true. Shutter speed has no effect on the flash (flash is faster than the shutter speed), but a fast shutter speed really knocks down continuous light. Verify your setup once so you can trust it. Pull out the sync cord once so the flashes do not trigger - then that picture with only modeling lights and other continuous ambient lights, should be very black. This f/10 1/200 second ISO 200 should not show any effect from the continuous lights, they are dim compared to flash. However, 1/30 second at f/4 likely will - maybe don't do that. :) At least not with the modeling lights on. The incandescent modeling lights are orange.
When framing the subject, my usual mistake is to crop too tight in the camera. Learn to leave a little space around subject, so the print can THEN be cropped to be 4x6 or 8x10 or 5x7 or whatever. All are different shapes, and we need a little space to work with. The DSLR format is 3:2, which matches 4x6 (portrait orientation), but 8x10 needs either less height, or more width. A bit of extra space can go a long way for cropping at printing time, and 12 megapixels can spare a few pixels for this.
Notions about Useful Items:
FWIW, I use a Sekonic L-308 meter, a less expensive model which is simple to use, and does anything I have use for. It meters the lights fine, see my review of it. The current version of it is Sekonic L-308X-U Light Meter with Deluxe case ($219). The discontinued L-358 was very popular, with extra frills I don't need. Except maybe one frill: L-308S is shutter-preferred only - which is required for flash, so that's great. But for sunlight use outdoors, you may prefer aperture-preferred, which the L-358 can also do. Still, we can simply select a different shutter speed on the meter, and then the L-308S will show corresponding aperture, so it's easy to make do working with the shutter-preferred meter on those few occasions when I want more than the camera meter outdoors (I really only use mine for flash).
The current replacement for the L-358 is the Sekonic LiteMaster Pro L-478D-U Light Meter ($370). An incident meter can be an extremely strong tool, especially for flash. Incident meters read the light directly and accurately, where reflective meters frankly often do not. (More about that).
I use a Nikon AS-15 Sync Terminal Adapter to add a hot shoe PC adapter to cameras without one, to allow use of a sync cable. You can save a few dollars on other brands, but the Nikon is excellent, it has a clamp to prevent it from slipping and misfiring. I also use it with a D800 camera that already has a PC connector, because the PC cable fits the AS-15 more snugly (much better), and the AS-15 gives no trouble. Both AS-15 and camera can use the screw-in PC cables, but I don't bother tightening a screwlock on the AS-15, it's not needed with camera on a tripod.
Storing muslin folded makes crease wrinkles in storage, so we store muslin by simply wadding it up loosely in storage bags (I use large plastic kitchen Glad bags), which creates many smaller random wrinkles, which might even look like an intended mottled pattern. Placing background at greater distance behind subject can hide wrinkles behind the depth of field. But I finally bought an inexpensive steamer, which is quite effective and recommended. And with the steamer, I have reverted to thinking loosely folding them is an easier better idea than wadding them up.
To hold the crossbar, Smith Victor makes these long 3/8" studs at right, which have 1/4" threads to screw onto the top of the light stand. Then anything with a 3/8" hole (this is the small end of a Da-Lite telescoping crossbar) just drops over these studs and sits on top of the stand. Studs are tall enough that nothing is going anywhere. A telescoping crossbar should fit into any available space (except it does have a minimum), this one is 4.5 to 12.5 feet long.
This type of "studio portrait" picture may not do well at Walmart. They may refuse to print this "professional" portrait, fearing you may have copied it from professional studio work in copyright violation. This refusal happens often on this type of picture, believe me (in the store, seemingly not so about online orders). It is not about the store policing you - it simply puts them at big risk, and their in-store employees are told "no way" (PPA sued Kmart for $100,000 about inadvertently printing a copy someone brought in, and that is the law now). They do have a copyright form you can fill out to assign their liability to you. But you are looking for better anyway, Walmart quality varies too much for this.
I would recommend www.mpix.com for printing your good stuff like this. They are very well known (legendary), and their 8x10 and 5x7 are inexpensive as any, and certainly as good or better as any. I always say Wow!!! They sure make me look good.
I hope this looks like an easy setup, because it is. Here is an older same setup in the cramped 15 foot space: