Hey, first off, don't worry about it, a lot of people feel this way.

the vibe as mentioned is a great idea. if you don't use toys get excited with your partner or by yourself. Also having an active vocal partner makes it fun. Have some kind of feed back; whether its words or him making sounds, touching or all three.
Don't jump right into the deed, ease you and him into it, lots of kissing around the area and use of the tongue first, play into it.
a great way to start is starting at the base and licking to the top and then encircling the tip with your tongue, this will also make it... um... "slip" easier which it make it more comfortable for you... and he'll love it too.
and when you feel done take a break and do it again when you're excited again.