1. Don't look at Americans, look at English/Italians wearing suits. Tailored stuff, no oversized pants please.
2. It's your friends wedding, not yours. Your day will come so don't try to be in the spotlight. Be classy but sophisticated.
3. No pleated pants. Really. I see a lot of Americans still wearing pleated pants. Don't do it. They make you look like you've borrowed Yao's pants.
4. A lower rise is a better look, wear your pants on the hips, not on your bellybutton.
5. No cuffing on your pants. Really. Don't, it's 2012.
6. Make sure your top fits. It might feel a bit too small, but that's supposed to feel a bit tight. Just make sure it doesnt wrinkle at the shoulders.
7. Get tailored or get a tailored look. It's a good look. Americans like to add one size to everything they buy. Don't.
8. Don't wear sneakers. It's not funny.
9. 3 inches width is the way to go for your tie.
10. Match your socks with your suit. You can look sharp untill a sock shows and it'll be all for naugth. Match your belt with your shoes. And match your shoes with good taste.
11. It's summer. Some says it's a rule you always wear an undershirt. Don't. You'll sweat more and it shows just as much. If you sweat much normally, try Nu Skin Antiperspirant instead of Deodorant and dont drink coffee prior to the wedding.
12. Wear your shirt as you do your suit: fitted, and if possible, tailored.
13. Buy a 2 button suit.
14. Get a haircut, get a slight tan and shave the evening prior to the wedding. You'll look as sharp as possible in a good suit, but you need to fix yourself as well.
15.get cufflings (of course a shirt that needs cufflings)
It definitely does help, I won't disagree with that at all. Especially in terms of suits. Outside of formal wear, eh....some of the best dressed people I know alter things they get from the thrift store and make it work.