For example, today I was the bartender at the speakeasy my kitchen became for my lovely sister's murder mystery party. As a dapper 1920s gent, I got my cross on:
I wore this with black jeans because that was all I had at home, but a button-up, vest, and tie would look amazing with a pencil skirt for business wear. Or even with plain jeans for casual chic. A fedora is also an excellent addition to many outfits.
If you're dubious, or need a better example than me, I offer up that most sultry of screen sirens, Marlene Dietrich.

Dietrich rocked a tux in every conceivable way. I don't know if I've ever seen a man who looks as stylish in a suit than she did (maybe Joseph Gordon-Levitt).
The most important thing to remember when you look into menswear styles is your own shape. Some bodies will fit well into actual menswear and more direct inspirations, while others might need a bit more tailoring and shaping to make a blazer, for example, fit like a dream. Personally, I'm mostly hourglass shaped, so a men's blazer that fits my bust will be very baggy around my waist, which I'm not a huge fan of. I need darting and structure for it to look how I want it to. It's one of those things that needs some trial-and-error or, as I like to call it, try-on-and-error!
Have any of you rocked it boy-style? Tips for anyone who wants to get her dapper on?
Don't forget that you can always ask questions and make suggestions in the comments or my askbox! And, if you like what you read, don't be shy about sharing it! E-mail/tweet/facebook/shout it out!