I'm a big fan of wearing men's shirts. They're comfy, and they can be very cute! Personally, I only buy men's clothes on sale or borrow them from my brother or father, though. They go on sale fairly often, and I don't want to bother browsing the entire men's section when I'm already searching the women's! But I definitely recommend trying out a men's shirt. They are amazing, and any girl of any body type can rockthe men's shirt!
The key is to pair it with girlier, more form-fitting outfits. The same general fashion rules apply - color coordinate, mix patterns if that's what you want, etc - but it's essential that you maintain a feminine figure when wearing menswear. Otherwise, you'll get looks in the street and hear people whisper "Is that a boy?" when you walk by. So add a belt, show some leg, or use girly colors and prints.
Of course, possibly the most important part of the outfit is the shoes. Don't wear men's shoes with your men's shirt! Even if the rest of your look is very manly, cute little shoes will give you a touch that says "I'm totally pulling this off - it's not a lazy day." And when in doubt, choose heels over flats.
And, with all fashion advice, it's important to remember that you can break the rules! Experiment with your menswear and see what works for you.
(The clothes in the images are from Urban Outfitters and Ruche)