This is a really important consideration ahead of a shoot. The most important thing is not to just put a load of random t-shirts into a bag and hope for the best!
It’s always good to bring a few choices. Even though in the style that I photograph is against darker backgrounds doesn’t mean that a black top wouldn’t work, quite the opposite.
Dark works great (check out my portfolio) , but bring some bright colours too, it all depends on the final look you want from your finished images. Formal, casual, moody, light, the choice is yours and I will be on hand to advise in advance and come the day. Bring a selection and make sure everything is ironed and looking good for when you arrive.