Most Helpful Guy
You need to take him and sit him down somewhere you plan to make out later. Somewhere private. And reassure him that you're not planning to break up with him or anything but you need to ask him... "Who taught you to kiss?" He'll either give a name, and you can say "Well, she clearly was a lousy teacher" That way you're blaming her, not him, and you can tell him you'd like to teach him some things...
OR, he'll say "No one". In which case you can go "Oh! That explains it!" Then touch his arm gently and say "Oh sweetie, I had no idea no one had tried to teach you how to kiss properly... you poor thing..."
Again, that's not as blunt as saying "You kiss funny." or "You're just not very good at it."
Get him to a place where he will accept that he's doing something wrong, and that you can teach him the way you WANT him to kiss... and then it's all about the practice.
IF he thinks no one is supposed to teach someone else how to kiss... show him that scene from Cruel Intentions where Sarah Michelle Gellar teaches Selma Blair how to kiss.. Show him YouTube, where there's thousands of videos, teaching people how to kiss.
Then it's simply a matter of teaching him good habits.
1) No slobber, he's not a dog.
2) Tongue is not obligatory.0THIS IS NOT RELEVANT ANYMORE