Have a garage sale! Put anything up for sale that does not have to go. The better you do with a garage sale the more money you will have to take care of the moving cost.
If a garage sale seems like too much work then look for a good charitable entity to donate your things to. Be sure and check with them to see what they need, that way you won't show up with a truckload that they can only use part of and you end up taking the rest back home. Usually there are several of these type entities in a given area; battered women's shelters, The Salvation Army and second hand stores are good places to start.
Another good idea it is to have a moving party once you've had your yard sale. Invite friends and neighbors and tell them that they can take anything left from the garage sale they like. It will be cheaper for them to carry the things your not moving away that may not have sold than it will be to haul it off to or pack it! Remember less stuff equals less cost and less stress.
Get the kids involved. Most youngsters have a room full of toys that they do not play with so make this a time to de-clutter their space.
Speaking of toys, not only do children possess them, you do as well. If you have a hobby that you really don't practice anymore, sell those items as well. Also think about items such as lawn mowers and yard tools; do you need them where at your new home? Sometimes they need replacing anyway and this is a good opportunity to turn the old ones into cash to help cheapen the overall cost of the move.