Here's another few silly habits:
This one involves a mod (Rise of Mankind: A New Dawn). I play this on Marathon to fully enjoy the eras in this mod, and I find that the AI is inadequate, even a difficulty level above me.
What I like to do is start out with a civ, reach highest in score by 1AD, and then manually change my control to the civ with the lowest score, and work my way up. I feel that the switch really spices up the game, because by 1AD, I am usually one of the dominant civs, and changing my control gives me a new scenario, new issues, and an opportunity to fix what the AI has broken.
I've tried this twice.
Usually, I set up the first civ I start with so adequately to the point where the AI controlling it dominates the whole game.
I don't know if I'm the only one with this habit, but every game I feel an intense need to do some colonization. I never play Pangaea, and Terra is probably my favourite map. Sometimes I will set up a colony in a place where there's a barbarian civ that spawned, and switch to the barbarian civ and play, "Defend your civilization from the highly advanced, rifle-holding conquistadores". That's fun too.