how do i make my bag keep its shape?

[laurenrambles.livejournal.com]

im planning on making an attempt at a smallish purse using my new (yay!) sewing machine.
while looking for some simple patterns, i came across one that called for craft fuse. i was planning on using a layer of a heavier fabric in between layers of light weight fabric to help it hold its shape... but that can be really annoying, and maybe theres a better option?

so the question is really: whats the best way youve found to get a bag (of any size) to keep its shape?
thanks!