What do I wear for a portrait session?
You are the focus!
You're the entire focus of your portrait. So when picking your outfits perhaps avoid wearing clothes that will distract to much from the real subject of the image. Wear something your comfortable and confident in.
Using tone to your benefit
Wearing darker clothing helps to bring more focus onto the subject of the portrait. Darker clothing also has a slenderizing effect in camera. Where as lighter clothing tends not to have that same effect. It does look incredibly clean in a photo though. A fresh white shirt can really make you pop! Avoid bright colored clothing as they can reflect their color onto your face when the light hits them. You don't want a green looking face just because you decided to wear your bright green shirt. (darker green will be fine though)
Using color to your benefit
The colors you choose are very important, and the colors people look best in really depend on the person. Try to experiment the week before your shoot and ask for your friends opinion on what colors you look best in. Try to stick with fairly neutral and calming colors. Colors that match your eye's are often very flattering. You could even wear small accessories that match with your eye's. And avoid overly matching your surrounding's, for example wearing green when your photo's are in a green forest.
Crazy patterns and logos
Complex patterns, logos, and decals all draw the viewers attention away from the subject which is not what we want. So please avoid wearing these things. Clothing with really tight grids or a small herringbone pattern can often have a moiré pattern effect on camera, so those would be something to stay away from. Keep it simple and clean. And your portrait's will turn out amazing.
Make sure they fit
Properly fitted clothing will do wonders for making you look amazing. Much more then a few camera angle tricks.
Layering makes for a diverse shoot
Feel free to bring two outfits as well. But even with one outfit, you can create a much more diverse shoot by bringing different layering options. Instead of having all your picture from the shoot with your clothes looking exactly the same.