The UK casting advice for what to wear to your headshot session is to wear plain, natural colours; this is because we need to make sure that we don't draw attention away from your face. The exception to this rule is White. Photographically it is a really difficult colour to photograph well. It is a very needy colour; it likes to be the centre of attention. It's great for fashion shoots, where the image is all about the clothes rather than the person wearing them, but it doesn't really work for headshots.
Advance apologies to Jack but I'm going to use a couple of his shots to demonstrate the difference. These two shots were taken during the same session, the only things that changed was his top and the colour of the backdrop. The white t-shirt in the first image makes Jack look paler, you can also see every fold in the top drawing attention away from his face. The dark grey shirt in the second shot is less stark, as a result Jack looks less pale and the attention of the viewer stays where it should.
But, sometimes white is just what you want. White sends out a message and if that matches the vibe you want to portray then it is the perfect choice. If your role of choice is in a gritty drama as a council estate drug dealer then white could be just the thing. I always chat to my clients during their sessions and Collette told me that her ideal role was a part in Eastenders. With this in mind this white crop top, with her hair pulled up into a high pony, transformed her into the newest resident of Albert Square.
Ultimately what I am saying is that your choice of clothes for your headshot is vital to not only compliment your complexion but to convey, to the casting agents who will be judging them, the type of role you want.