Solid color short-sleeve T-shirt and non-matching solid-color elastic-waist gym shorts, usually -- I try not to draw attention to myself. Though for PL club workouts sometimes I wear a homemade Bad Brains T-shirt (vintage group photo of the band, no logo). And I'm gonna get a "Miskatonic University" T-shirt I'm gonna have to wear. (Miskatonic U is constantly mentioned in H.P. Lovecraft stories).
Shoe-wise, crappy Avia cross-trainers or low-top Chucks, depending on what I'm doing.