At the start, choose the kit with blocks and buy some more blocks as well. Get some armour and then gold. Once you get enough gold for 5 obsidian (on OP it's 15), build an egg defence. Then, get some TNT, a sword and a pickaxe. Get more blocks if you need to. It's early so people most likely don't have obsidian. Tower to their base and place the TNT above their egg (bomb it). When it blows up, break it and kill them. If you're on Cave, late-game you need a farm of diamond generators, linking up the 3 islands and the middle generator of those islands and collect enough diamonds for armour. Get a punch bow, diamond sword+pickaxe, and diamond armour. From there, you can kill them easily.
That's the Enderman strat. I take all rights to this strat. This strat is copyrighted by Ender (2020-21).