Think about nothing at all but the kiss you're kissing. Better yet, don't think.
Start with lips either just slightly parted or closed. Don't start wet, with your mouth gaping open and your tongue poking out.
Relax your lips, but don't let them mush up.
Kiss as though you have all the time in the world.
But don't prolong a kiss beyond its natural life.
Wherever your hands are, use them; slowly increase pressure or graze gently.
But in non-erotic zones, like the back, the shoulders, the arms.
Don't turn every kiss into a sexual act or overture.
Once in a while, pretend it's the first time you've ever kissed this person.
Open your eyes (IF you can stand the intimacy).
Kiss your partner's face in places other than the lips.
Two or more little kisses are a nice way to warm up to big kisses.
Enjoy several long, slow kisses before moving into nibbles, licking, and ... whatever.
Add another "little kiss" or two after the big one. Kissing doesn't begin and end abruptly.
Attend to a graceful finish -- a soft, smoochy ending is much, much nicer than a dismissive smack.