What to say to my partner who isn't a good kisser?

I like kissing quite a bit and I really like my partner but whenever I go in for a kiss it's usually less than satisfactory, he opens his mouth way too wide and pretty much crashes his face into mine and he's really sloppy with it and then he pulls away way too quickly and starts giving pecks down my neck, which I actually do like, but the actual kissing part is... Eh. I know he's never had a girlfriend before so I don't think he's all that experienced which would explain a lot of it but I'm usually pretty shy and uncertain when it comes to talking about this stuff so I want some advice on how would I bring it up and what would I say?