This is just my personal opinion, but it's actually quite hard to stage an actual
kiss for a photograph without looking a bit derp due to the positioning of the mouths etc - I agree with Surfsama
that an almost-kiss often looks better for a photo than an actual kiss. (This actually solves your problem as well DazzlexMe
Here are a few pictures of me doing an almost-kiss shot with one of my friends:
(These are older photos and when I look back at them I think "we should've leaned in closer!" but you get the general idea).
We've also done a sultry-ish prior-to-kiss shot: like http://fav.me/d3btkhy
For these kinds of shots I don't think it matters whether or not you've ever kissed someone before, because I was doing kiss shots like these even before I had my first kiss. In the end both parties are pretty much like actors in a role and your aim is to bring that emotion out. You want to look at the photo in the end and even without the lips touching you can tell that the kiss is there, if you get what I mean.
If you're hoping to do a photo of an actual
kiss, then I recommend a very soft kiss (it's obviously entirely possible to do this even if you want a very high-tension passionate scene, because you can still convey that passion through your body language and pose), simply because I've seen a lot of actual kiss cosplay photos and the mouths eagerly mashing together don't look that flattering ... at all.
Just my two cents!