definitely figure out if you have a strong gag reflex. I do and the first time I tried to deep throat... well let's just say I know where to stop now
Speaking of that, anyone know how to kill the gag reflex? Partially... as I realize it's an important part of keeping me alive
As to what to do, if he's uncut, be careful. If you suck too hard while holding back his foreskin you can cause minor ripping along the inside of the foreskin. And while he probably won't feel it too much during sex, it's very very agitating afterwards.
For most uncut guys I'd say let the skin move normally, don't try to hold it back. Also if jacking him off while sucking the head, again be careful of pulling too far back.
For general tips on giving head, be aware of what your tongue can do
I usually do 10-15 minutes on the dick in many different fashions, and then will switch to the balls. The go back to the dick, and while the balls are still wet, gently stroke them with one or both hands. The saliva generally helps my fingers slide smoothly and softly over his balls