That said, I know not everyone is as fashion-obsessed as Mr. Purple Suede Loafer, so I think there are some simple guidelines you can follow:
• Casual Shoes: desert boots, toms shoes, vans (a good alternative to loafers), boots (with long pants), oxfords/tie-ons (brown or tan) and flip-flops (if they aren't dirty and beat). I know some women would really disagree with the last one, but I for one am not scared by manly feet. In fact, I like them. If a man's toes were pedicured (i.e. prettier than mine) I would be completely weirded out. Men need their toes to breathe in the summer just like ladies and you don't have a lot of options for that (see "The Bad"). (exhibit B- you in your Clarks, Jon ;)
• Fancy dress: Keep it classic. Black with ties. Not too pointy or too blunt. An elongated, rounded toe with a matte leather or pleather can look very Cary Grant (swoon).
• Styling: For fancy dress, your pants should hit the top of your shoes without folding/creasing much at the ankle. For casual wear, in the winter make sure your pants cover your socks. In the summer, shorts go with all of your casual wear options, but (and this is a big but), your feet must be sock-less. You must go sock-less. If you don't, socks can be cruel to a man who isn't going for that professor-at-the-beach look. Socks cut off your line (shirt, shorts, leg, sock, shoe= bad) and kind of makes you look overdressed. Go sock-less with pants too. A man's ankles peeking out from under rolled pants or shorter pants is dapper- really. (exhibit C and D).
• Grubby old flip-flops, Birkenstocks or other leather sandals (the gladiator look only worked on men when they were being eaten by lions in a Roman coliseum), black socks with brown shoes.
These are personal dislikes that some girls might be okay with. I have a strong aversion against the following: Crocs (unless you are a chef in the kitchen or watering your lawn), boat shoes and/or loafers (just looks plain pretentious to me). The worse offender? Sandals with socks. That is never okay. Are your toes cold? Wear shoes. Tevas should be hidden in the recesses of your closet until you go camping. Tevas are another reason I don't like camping.