Depends on where it's from & what you are looking to do with it. If it's found outdoors, boiling is a real good idea, gets rid of any nasties that you wouldn't want in your tank.
If you are looking for decorative purposes, you probably want it to stay on the bottom. I drill a hole in a piece of slate, and attach that to the driftwood with a stainless steel screw. You can try soaking it in a bucket of water, it may take days to weeks before it becomes waterlogged enough to sink.
If you want to add tannins, that brownish tint, add it right after boiling, if found outdoors, or rinse it & toss it in if you bought it from your lfs. If you don't like the tint effect, soaking with a daily water change helps, as does dousing it with boiling water. It will still leech some tannins, just much less.