The main problem that guys face when trying to kiss a girl is knowing if they're ready. Get the timing wrong, and things will turn awkward. Get it right, and well... you'll know. Here's how you can increase your odds.
Step 1
Make her comfortable with comedy but not too much - humor is statistically the most attractive quality. For instance, it's probably not a good time to kiss that girl when you're watching a movie where someone is being killed. Use a nice, romantic spot. Who doesn't like a sunset, an empty grassy meadow under the stars, a deck on a lake at night,on the beach, a paddle boat at a friends pond at night, a private camp fire...you like her. Caution though, she will like it. But if she doesn't seem to like it, resume what you were.
Step 2
Stare into her eyes and move gently closer to her. Better to not ask a girl to kiss you, because that ruins the moment and you might lose your kissing chance. A kiss, especially the first, is about the risk. It's about taking the chance with the girl and, hopefully, she will respond in a positive manner. If she doesn't want to kiss you, you should be able to figure it out through body language.
Step 3
Put your hand on her cheek.
Step 4
Go for it! Lean in for the kiss. Try a peck for your first kiss, then move on to longer, more passionate kisses when you're both ready.
Step 5
Use the other hand to stroke her hair or neck.
Step 6
Pull away. Look deep in her eyes. You want the romantic way: "Thank You." You want the funny way: "... cool." (but not in a snobby way). This is up to you.
Step 7
Find what you were talking about before and keep going if you're not kissing anymore.
Step 8
Remain normal after the kiss. You don't want to leave any sort of bad impression.