If you're about to ejaculate then tell them, or at least signal that it's about to happen. Always let your partner decide whether to stay down there for the main event. If you're happy to go down, don't lose sight of what's going on upstairs in his head. Frankly, you're tugging at his brains down there, so you need to pick up on every moan or groan he gives. The better you understand each other, however, the more comfortable you'll feel.
Many people gag at the idea of going down on a dick.
Even if it's clean as a whistle, there's always the fear he'll forget himself, leaving you to deal with an out of control organ with no apparent off-switch. TheSite suggests you grip his penis head as you approach it, and hold it there in a ring formed by your thumb and forefinger. Once he's in, feel free to place your hands around the penis shaft. This gives you control, allowing you to determine how much you want to take into your mouth. Use your mouth What goes on when you're down there is entirely up to you.