I like guys in casual clothes that FIT. A lot of guys wear stuff that's too big for them - jeans that show off your ass are a good thing! It doesn't matter where you shop, now a days even Walmart has decent graphic t's and d***ies. (Keep in mind, a girl who is a brand whore WILL care what brand's you're wearing). Stuff like American Eagle, or Billabong, Etnies, and other sports brands are great as well!
Well, I'll name specific styles, not brands. And I'm not in my twenties, but guys should look mature and like they put thought into their outfit. Polos are good, so are skinny jeans, and vests (you have to be able to pull that off though.) Oh, and untucked button downs are a total WIN. I love them.
I like long-sleeve t-shirts with the sleeves pushed up, not-too-baggy jeans (most definately not skinny jeans), t-shirts that show off your muscles, and button-down shirts/polo shirts. NO flip-flops, please. Gym shoes are best. <3
Okay so most girls in their twenties like a more mature look like polo (styles like that) I know that those are expensive so you can always try shopping at ross and tj max for the same look but cheaper, hope this helps:)