Buy more boxes and tape than you think you'll need (from somewhere you can return).

I don't know why this always happens but somehow when you're packing you use all of your boxes and then have to go out for more so you get a few more and then you realize you're out of tape so you go out for that and then you realize you need even MORE boxes and so the cycle continues. Instead, buy way more boxes and tape than you think you'll need and return what you didn't use. Chances are you'll use most of it.