Peel a banana and practise on that. It will be about the size of a man's penis, unless he's really big or the banana's small... See how you can avoid putting the teeth on the surface of the fruit. Plenty of spit is needed, so don't have a dry mouth, of course.
Use your tongue to excite the head, and the shaft, to lick or wrap, or lap...
Then most people think that just licking and sucking will do the job. While the sensations are certainly very pleasant, you might need to remember to use your hand and fingers up and down his shaft to keep the blood pumping, the excitement happy and you'll definitely know when you're getting there, because the texture of his penis will change and get very much more tense and ready.
Lastly, if you don't want to swallow, or are not sure you want to swallow, retrieve the penis before he ejaculates. Ask him to tell you when he's going to do so, if you're not sure. And finish the job off with your hand. Have towels or handkerchiefs within easy reach.
Good luck, good suck.
miley-eating-icecr