I am white, need input from blacks about how to behave at black family reunion?

My best friend is black and I am white and I have no other friends and he invited me to his family reunion because he is nice and his family is nice but I've never been around more than one black person and I need input on how to behave please? Should I dress casual or in a suit? I wanted to wear the same Kyle Busch t-shirt I always wear because I like Kyle Busch but since most black people don't like nascar should I wear a different shirt? I have a shirt with lions on it do black people like lions? I was also going to bring something, do black people like artichoke heart soup?