1. Go for a brighter shade that is almost in the orange family (versus a dark red with purple or blue undertones). Think Sienna Miller. (Heart her!) I'm loving MAC's lip pencil in Brick. It's so flattering and gives a lot of control in the application because it's a pencil.
2. Don't forget the corners. When you open your mouth, you don't want to look like a painted up clown. Your whole mouth should look cherry stained, so don't skimp on the coverage. (If you're worried about getting it on your teeth, you can execute the ol' finger pull. But using a lip liner to cover these areas should take care of business.)
3. Once you've applied, kiss a tissue. This will keep you from getting lipstick all over the place, as well as subdue it a bit. (I also swear by holding a tissue over my lips and dabbing over it with some face powder or blush on a brush if I'm worried about it smearing.) This color tends to tint lips for a while, so embrace the various stages of wear with red. It's more low-fuss than most think.
4. If your outfit or occasion calls for a darker eye, forgo the red lips with that look. Don't overdo it. IMO, the best pairing with red lips is soft pink cheeks and a neutral eye with a few coats of mascara. Keep everything matte and clean. In the words of Paul "Koonu" Rudd in Forgetting Sarah Marshall, "Do less."
5. Make sure your lips are hydrated. This look goes from hot to hot mess really quickly if you've got parched mouth. After you brush your teeth in the morning, immediately apply some lip balm. By the time you're ready to go for the red, they'll be softer and look lovely.
6. Own it! If you don't feel confident in this look, don't do it. That goes for everything, really. Be you!