If you can, one place for boxes, one place for stuff that you want to get rid of (Freecycle is great as they come and get it, and people will take big mixed piles). Get some of the boxes that are hanging wardrobes (any of the removal/storage places sell them) so that your clothes will just go straight in them.
Get a skip so that the rubbish can go straight in there.
Cleaning the new house - bribe all your friends to come and clean with you (wine, beer and curry seem to work) one weekend. It's a good laugh, and amazing what you get done