If you need more drying power for a big tub that you open often, or all the desiccant packets you've saved become exhausted, you can make potent drying packets from the silica gel sold in craft stores to make dried flowers.
I put a tablespoon of silica gel into a paper coin envelope, or you could just fold or roll a smaller amount it into some paper and tape that closed.
http://garden.org/ideas/view/R...
You can also bake rice until it isn't-quite-brown, and use that as a mild desiccant.
There are also humidity cards with colored spots to show you how dry your jar or tub is.