Couples and families should coordinate (for example, different shades of the same color, or complimenting colors), but should NOT match (no need to wear the exact same shirt or color). A print is OK as long as there aren't competing prints (an idea, choose one print for person, then have everyone else wear colors from the print). Avoid busy or tiny prints (like plaid men’s shirts).
For children, avoid clothing with pictures on the front (otherwise half an animal face may be cropped out). Smocking or small details (like flowers on a dress) or a simple print are OK (and personally I like plaid shorts and solid shirts on little boys). Lands End is my favorite source for classic girl's clothes.
Solid colors look best for groups, the more people in the photo the more simple you’ll want the clothing and the more skin you’ll want to cover (long sleeves and pants).
Dark jeans for adults are generally a good choice. If you wear a dress or skirt make sure it's long enough to sit in.
Long sleeves look best, short sleeves are a good compromise, and women, only go sleeveless if you're OK with the size and toning of your arms. Or bring a wrap that can be used to hide upper arms.
Fit is important, as anything too tight or too loose will be noticeable. Men's dress shirts that are tucked in often look puffy. Keep in mind that you'll be moving around so stretchy tops are often better so they aren't wrinkled and folded.
Clothes should also appear new, even if they aren't. If the color is fading, or the sweater is getting fuzzy, that will show.
Wear colors and clothes that you feel good in and that look good on you. Please avoid white as it's brighter than skin. The brightest spot in the picture is where the eye is drawn. Lighter colors appear larger, darker colors fade back, so keep in mind what you are highlighting.
Avoid shiny fabrics that reflect light.
Layers can look good on any age and add some texture and interested to an outfit. A three piece outfit looks complete.
And remember, shoes will show! (so wear cute ones and please no tennis shoes)
Feel free to run your clothing ideas by me or bring several options with you to the shoot.