Set aside a closet or small room and put all the stuff you DON'T want them touching there. Lock it, duct tape it, something - seriously, they will just start throwing things into the truck at the last moment if they can get in there.
Keep the vaccum cleaner out. You can vacuum/clean as they clear out the house. If you don't have room for the vacuum in your car, they'll pop it in the truck at the last minute.
It was said before - but definitely take out the trash. They will pack up your trash cans with or without the trash. I've also seen them wrap toilet paper rolls in several sheets of packing. They get paid for the amount of packing they use, so my experience is they use it liberally.
Ask for stand up wardrobes for your hanging clothes. Otherwise they'll toss everything in the bottom of a box.
Separate your professional items (books are the heavy points here) so you don't go over your weight limit. Your limit is probably not in danger unless you have a full household complete with outdoor items and heavy sporting goods or weights or something.
Roam your house as they pack. Being there tends to make them take more care of your things.
I usually get them some drinks, Coke and water or Gatorade, and a few pizzas for lunch. Good will goes a long way in keeping your stuff well cared for.
I tell them which restroom to use. That lets me clean (or keep clean) the others.
Take digital pics of your house a few days before they get there. Put special focus on the big, expensive stuff, but just having the pics will usually be enough. I put this on a thumb drive and carry it with me.
If you have room in your POV, do a partial DITY for all the stuff you are going to carry yourself. It is usually more than worth it and not too painful. In truth you'd end up carrying the same stuff and just not get paid for it if you don't.
When you get to the other end, they are required to put your funiture down once and to unpack and remove the packing for anything they packed. They won't want to, but unless you want to deal with the massive amount of packing and boxes, I would recommend pushing the issue. We end up doing about half of it and then hubby gets annoyed with them and kicks them out of the house so we end up having to get rid of the other half of it. Ugh!
That's all I can think of right now, but if I think of something else, I'll put it in up. This is coming from some 12 yrs of military moves experience... FWIW, the movers have done less damage to my house than my children have.