1. Whatever you do, GET A WINDOW SEAT
If you're in the aisle, your seatmates will no doubt have the world's smallest bladders and will climb over you every 10 minutes to get to and from the bathroom. If you get a window, they won't pee, ever. Which will be incredibly annoying, but it doesn't change the main idea here: just get that window.
For your best shot at one, set a reminder 24hrs before your scheduled departure, as most airlines will let you check-in and choose your seat then, even if you don't have fancy-people status with them.