I can't offer advice on how to draw them correctly, but the kiss drawings I've seen that I'd call bad are the ones where they appear to be coming at each other shoulder to shoulder. When you're kissing as above (as opposed to certain sexual positions), your hips are facing the other person's hips. It's implausible then that your torsos would be curved in such a way that you'd be kissing from the side.
(I've generally put this particular tic down to the artist insisting on drawing breasts in the scene even when breasts would not be visible.)