If he follows, put money in he'll lock the door, and the rest comes naturally. If no glory holes, stroll around and make eye contact. A finger tapped on the hole means he wants you to stick your dick through so he can suck it. Insert money and do whatever feels natural. Go into one of the booths with the glory hole-if he's interested, he'll go in the other side. Walk around and scope the booths-are there glory holes? Which booths? Are people in there with doors open? (if not, two possibilities: it's one of those places where you'll get beaten up for asking, or the cops have been patrolling and the doors have to remain closed.)