I once dated a guy who hated blowjobs. Wouldnt let me even try. I was sad :(
But anyway I guess that goes to show that, contrary to popular belief, not every guy will be bothered about blowjobs.
As for coming naturally, no not really it takes practise and experience to get it right. (I say get it right but...) It will take a little while to overcome the initial apprehension. Things like worrying about hurting him or your teeth in the way or gagging or any other worry.
Then it will take a little while to learn a technique and just like us women, not every guy always enjoys the same technique. (Although they seem a bit more lenient than us ladies and generally just enjoy the fact that it is in your mouth...generally) So thats a learning curve you share together.
Just be honest with your guy and tell him you want to learn. I am hedging my bets that he will be very grateful to teach you. Ask him afterwards what felt good and what didnt etc.
But my overall general advice is to relax, focus on the head of his penis, use your hand at the same time to give him added stimulation, dont be afraid to drool, it makes things easier on both of you if its nice and wet, dont suck too hard, just gently, otherwise you will end up with a massive jaw ache within a few minutes and unable to continue with the pace, plus it might be too intense for him. Go at your own speed and comfort level with regards to depth. Nothing will put you off a blowjob faster than a guy pushing your head down and making you gag. (Thats not polite boys ;) ) Eye contact is good but it doesnt half give you eye strain sometimes lol
Oh and something about not neglecting the balls.....
but the mostest importantest bit of advice I can give is "enjoy it" Men aint silly, they can usually tell if your giving a half hearted blowjob or a quick lick for 10 seconds in exchange for them going down on you or whatnot. I mean if you dont like it, say so. I think that is the biggest complaint I have heard from men regarding blowjobs, and can you imagine if the tables were turned? I dont think I could feel sexy. As for swallowing, again thats your choice and I think the general sense I pick up from men is that swallowing is of course the nicest, if not, let him come on his belly or something, but I think holding it in your mouth and legging it to the bathroom before making voilent spitting noises is considered the worst lol.
Have fun x