Kissing is like totally important for sex. Some of the best and most memorable sex I've had was while joined passionately at the lips and the hips. But too many people suck at kissing. Sometimes literally and in a bad way (there is a good way to suck).
Things NOT to do while kissing:
-bash teeth together
-give them a hickey on their lips/tongue
-try to clean their teeth/touch their tonsils with your tongue
-slobber on their face/dribble into their mouth
-attempt to suck their teeth out through their closed lips
-press too hard and crush their mouth
-do that "pucker" kiss that chimps do
-have dry lips/mouth
-breath out into their mouth
-have bad breath
-have food still in your mouth (unless it's gum)
-cough/sneeze/choke
-keep your eyes open (this is just totally freaky)
-too many other things to list
Sadly, I've had ALL of these things happen to me. Not good, though some are more forgivable than others. If you can think of anything someone has done while you've been kissing them that you haven't liked, don't do that.
So how to kiss? There are no hard and fast rules, but I find the trick is to start gentle, and work your way up to tender, and then sometimes to passionate.
Gentle: Gentle kissing is nice. Call me a softy, but I think it is so **** you. When I think "gentle" kissing, I imagine hovering my lips really close to hers for a few moments while looking into her eyes, before softly touching slightly moist lips, lips subtly puckered and slightly parted, brushing my lips against hers a bit, softly pressing together, brushing my nose against hers, perhaps a little sucking on her bottom lip, or casually sticking my tongue out a bit and licking her just a bit between her lips. Maybe I'll move a bit away from her mouth, down her cheek and along her jawline, then down her neck, doing those little "muah" type kisses, but softly and slowly.
Tender: Tender kisses are also good (I like kissing, shut the **** up). When I think "tender" kissing, I think "restrained intensity". Like there's a passion there, but it's being held back, and manifests as tenderness. Kissing is more firm and slightly faster (slightly), with perhaps some pulling of her bottom lip with your lips, licking the tip of her tongue between both your lips, maybe getting a better "seal" around the lips by tilting heads at an angle. Mouths are still kept only partially open though, no gaping like you're trying to swallow her head. And not like a frankenstein, with mouth held in some locked position and tongue flailing. Picture how fish open and close their mouths. Kinda like that, but less "fishy"-like. Like you are tasting her, almost trying to massage her mouth with your lips.
Damn, kissing is seriously hard to describe.
Passionate: Passionate is deep and heavy. Almost anything goes in passionate kissing (except the things I listed above that should never be done). Wrestle each other's tongues, suck on each other's tongues (very gently and sexy-like, too hard can really hurt), tilt heads at right angles and see how much of each other you can devour before smashing teeth, whatever. Softly bite her lips, swap gum (or wrestle each other for control of the gum, which can be fun and is surprisingly hard), etc. At this point you're basically just mouth ****ing each other until you can start ****ing for real, so as long as you don't **** up by doing any of the "don't do's", you'll be fine.
And if she smashes teeth with you for the third time, lose the *****. You do NOT want her mouth near your ****.
But there's more to kissing than just the lips. Hold her hands with your fingers intertwined with hers, hug her close with your arm in the small of her back, run your fingers through her hair, caress her neck, cup her face with both hands, hold her chin in one hand, hold her hips/waist, grab her ass, pull one of her legs up against your side, support her back and lean her over backwards, hug her and lift her off the ground, stroke her arm or cheek, run your fingers down her sides, hold her hands above her head while against a wall, etc etc. A good kiss is a whole body experience for both of you. In fact keep this in mind for everything about sex: it's always a full body experience.
