Here is what we did:
Step 1: Find Free Pallets - try the following locations; furniture stores, hardware/building supply stores, magazine/printers/publishers, or anywhere they have pallets of 'stuff' to unload. I suggest calling first to save you a trip, find out who you need to talk to and if they have any to pick up.
Step 2: Level the ground
Step 3: Size up the pallets - unfortunately they are not all the same size and the more uniform you can get them the better for a level deck.
Step 4: Put pallet in place - check level, then put on the plywood and so on.
Step 5: Put ending boards all the way around to cover the pallet up.
Step 6: Paint or stain.
Step 7: Enjoy!