Once I'm satisfied a guy's hot for me, I grip his cock in one hand and start licking the head. I run my tongue back and forth across it, occasionally running the tip of my tongue along its ridge.
Make sure you have plenty of lube and use your palm to rub circles on your head. It feels amazing doesn't it?
I'm always very careful when I do this not to let-err make a guy cum. I keep it up for a good four minutes, pausing if I have to, making sure I coax out a lot of precum.