i absolutely love that baseball-style hats are coming back. i never really liked the way they looked on me, but now that i'm getting to know more about them, they're growing on me. take a look at some of my favorites: (click for sources)
pair a classic striped dress or colored tweed jacket with either a similar color cap or a contrast color. i love the way naomi styled hers for the Sonnet James Lookbook.
pair solid colored pieces with a patterned cap to keep thing interesting. a patterned hat can also dress down a more fancy outfit, or keep up the casual. long, soft waves are my favorite look with baseball caps, too. (but that's bit of a problem because i don't have long hair...)
and this is the ball cap i'm lusting over right now. just thought i'd let you know.
i hope this helps you all better style your caps, and inspires you to go and buy one, like right now... xo. Molly