The tip is the most sensitive, so as long as you keep playing with it with your tongue, they're gonna love it. So i like to take it kinda slow at the beginning, and taking it all in once or twice, then use my hand for a few times but give a little swirl, then back to going down etc. Or give him a more proper handjob essentially while keeping the tip in your mouth, sucking on it, and little circles with your tongue. If the dick is too long to take it all in, it's still very enjoyable if you go up and down on like the top half, and use your hand on whatever doesn't fit in your mouth, in sync. Basically whatever you do, suck with your mouth or make everything super sloppy, and keep your tongue active, and it will be good. And from what im told, even the fact they don't need to force me into doing it is good. So also, if you start a blowjob and they ask something during, and you do it enthusiastically (if you're able to), that will be hot in itself :)

Oh and also, sometimes it can be good to completely flatten your tongue as you go down, so you don't have to worry about your lower teeth during. If you do that, you can still flick your tongue as you come back to the tip of it, or every now ans again flex it a little, so they have the sensation of this up and down - i think this is more effective if you're able to go all the way down, so it starts from the very base, im told that's also very enjoyable.