What to do with my flat hair?

I have medium length, sort'of layered hair. I have to keep my hair up. (golf practice) I was going to do a bun, but then my hair looks WAYY too flat for that. My hair's usually thick. No answers with shampoo or taking a shower. All I have right now is a straightener, and a comb, if I can find one. I keep my bangs off onto the side, and I have to wear a visor today. So please help!! Thanks. ;)