» Choose a color scheme, more specifically, pick a couple of colors and choose clothes that fit in that color scheme. 
» But don’t be too matchy, matchy. You should avoid having everyone wear the same color or outfit (this goes for matching kids’ outfits, too). 
» Avoid clothing with logos, characters, or catchphrases (e.g., a big Nike swoosh), as these can be distracting and will date your images. Think timeless and classic.
» Patterns can be fun and are a great way to add visual interest. 
» Textures (e.g., knits, lace, corduroy, velvet) are another great way to diversify a wardrobe and they photograph beautifully. I especially love the way knits show up in images, and they are great for layering as the temperature dips on summer evenings. 
» Layers, hats, and accessories (like scarves) will keep everyone comfortable when the weather or temperature shifts, and have the added benefit of introducing more personality into your session images. 
» Keep your location in mind, some styles are better suited to a more natural environment and some just fit urban settings better.
» Most important of all though is to remember that these images are meant to be a reflection of you. If you choose something wildly different than the types of clothes you would normally wear, you likely won’t feel as comfortable in front of the camera.