I like to get on early if I'm not already super comfortable. A: Get comfy, get drinks, and get to sleep or into a book. B: Turn off all the TVs in vision since half the people don't actually watch and won't figure out how to turn them on.

Also I've found that a lot of people have an affinity for taking the better seats (last row of front cabin on a lot of United's fleet has space under the seat in addition to in front). While you can let them know and ask them to move, it makes you feel a bit like a jerk, especially if they switched seats to sit next to a companion. Or if they got "confused" and took the other side to avoid the sun and then say "oh I'm sorry, do you mind taking mine or shall I move my stuff over to the other side of the cabin"?

This doesn't seem to happen in proper First cabins.