Water them a couple of days before the move so that they can dry out a bit before you pack them in.

The most important factor is to prevent the plants from tipping, shifting, banging into each other, etc. You don't want to have to worry every time you step on the breaks.

Any plants that are especially fragile should probably be boxed separately, surrounded by plenty of newspaper. Newspaper make good plant packing material, as it breathes. Pack smaller plants together in open boxes, also surrounded by newspaper so that they don't crunch each other.

Paper bags can also be helpful in protecting plants. Again, newspaper can be used to keep them from toppling and shifting.

I'm sure that others have some good ideas, too. Good luck with your move!

How did the move go?