Being prepared and packing.... My routine is simple: I pack in one step. Whether it's two days before I leave or 20 minutes, I do it one time so I don't forget anything. Dragging out packing over days is a recipe for forgetting something. I can usually pack in <15 minutes from start to finish (assuming things like laundry are done). My wife on the other hand is a trainwreck and every trip together with her starts with us leaving the house (late) and her screaming and hysterical... and usually forgetting something major. Her last trip I had to Fed Ex her LAPTOP to her....LOL. How on earth does one forget that?
Anyway, I suppose my OCD is packing/planning. I'm also kind of a nut about getting to the airport early but a lot of that is that I actually enjoy hanging out and having a coffee or drink in the lounge (and have to build in a large buffer for previously mentioned wife).