Really, I think you should try it on yourself, first. Figure out what you like. He’ll pretty much like the same things.
Besides which, not all guys are the same. For example, I like to be rubbed slowly and touched lightly, with fingers or mouth. In porn, I often see women going so fast, and it seems so rough to me. It makes me hurt, and I’m not even being touched. But, I guess, some guys must like it fast and furious. Some guys probably even like sandpaper. No joke.
Some guys like their balls to be sucked. Some like light tickling behind the balls. Some like their asses fingered or penetrated by fingers. Some like their nipples sucked while stroking them. Slipperyness is real good, and if it comes from natural lubrication, that might be better than artificial. Depends how fast you want to go. Personally I prefer it slow, and once the lubrication appears, for a little bit of speeding up (just a little bit) and also to start stroking more towards the base of my penis.
When I first discovered masturbation, it was because I was lying on my stomach on a soft, cloth sleeping bag. I was 13. I must have moved my penis on the cloth a little, and it felt good, so I kept on doing it. Boy was I surprised (and delighted) when I came!
After that, I kept on doing it lying on my stomach (spitting in my palm for lube) and dry (wet) humping my hand. Later in life, I discovered the delights of doing it with just my fingers, although, that was easier when I was watching porn.
Anyway, whatever you like on yourself, your bf will probably like. And I know you said you didn’t want to talk about it, but believe me, if you do talk about it, and if you can ask him what he likes, it will be so much better for the both of you.
Also, like @sjmc1989 said, looking like you really enjoy what you’re doing to him, will turn him on, even more. Like if you get excited by him getting excited. Perhaps if you are pleasuring yourself at the same time. It’s very hot! When my wife cums, it usually make me cum, too.
Also, and some people might think this is gross, but when he does cum, if by your hand, you may want to lick it up. That’s another symbolic way of showing how important he is to you, and if you act like it tastes like nectar, he’ll probably want to do it again, right away (unless he has issues about that kind of thing)!
It’s all about atmosphere and theater. It’s about making someone believe you just can’t get enough of them, and you would do anything for them. It’s about making them feel like the absolute center of your world. I could talk you through the whole thing, atmospherics and all (I think I have a talent for that kind of thing), but I think that even I am not willing to go that far in public (or private, for that matter, except for people I know extremely well).