With a hat tip to Apocalypse World:

Give every NPC a name.

I don’t mean, necessarily, a personal name. That goblin over there might not even have himself a Christian name. But don’t refer to him as “goblin 1.” If not personal names, give them descriptive names. Make them up on the spot. Maybe you think, “Oh, man, this goblin, right? He’s just got one arm! And this other one’s only wearing half a leather cuirass like it’s some chick’s half-shirt or something.”

Don’t worry about making them memorable; just try to make them distinct. If you come up with “sword goblin,” that’s fine! It’s the goblin with a sword. But you’ll have to think of something in case he’s disarmed. Maybe “the goblin formerly known as sword goblin.”

Don’t say the label.

If the players are searching for the trap and find it, for goodness’ sake don’t say, “You find a trap.” Instead, say, “When you rip through the pelt, there’s nothing underneath, just mud and rock about 20 feet down, with a bunch of  skulls littered around and femurs stuck into the ground pointy end up.”

Yes, it’s a pit trap, but isn’t this a better thing to say than “pit trap?”

The reason you do this

is to keep the players grounded in the fiction as imagined. The more I hear about “bandit 1,” the more I think “this is a game.” The more I hear about the “guy with the mismatched boots,” the more I’m thinking about the fiction as such—what things look like, smell like, feel like.