Mopani and Malaysian woods are very good for a tank with panaques (royal pleco, or other wood eating plecs) as they are very dense, so not only do they sink well, they last a lot longer.
Ironwood is a no no, it is very toxic, but I doubt you'll find any of that around. Cedar I would avoid also, since it's a very perfume wood..
If this is wood you found, then you must make sure it's not still green in the middle, particularly important with silver birch as it contains some pretty thick oils (you can burn a piece of it, and hold a wet piece of paper over the smoke that comes off, You will see if there is an oil on the paper, you've probably seen this cooking hotdogs while camping and used silver birch bark to start the fire, quite disgusting..)
The harder the wood the better, but the longer it would have to be exposed to the elements (aka adrift).
Once you have the piece, make sure it's rinsed free of all sand and other visible contaminants, then boil the wood for no less then 1/2 hour (you can add salt to increase the temperature if you want to be very safe) then let stand in the water for another 3/4 hour, this will heat the center of the wood up to burn off any pesky insects/parasites.. (last thing you want is termites in your tank)
once that's done, allow it to cool down and soak in room temp water for 4-6 hours, you may add salt.. then rinse the wood thoroughly and you can put it in your aquarium..
If you are buying it from a petstore (can be very expensive) then you could soak it in very hot water for 3-4 hours changing the water half way through.. If the discolouration of the water is not what you want, then repeat this every couple of hours, the hotter the water, the faster it will bleed out the tannis that causes the discolouration.
I've written this as I went, I hope it explains a good chunk on using found driftwood in your tank as I understand it.. (If I missed anything, please feel free to add to it) I prefer not to use bleach since that can cause the wood to weaken/rot... (not to mention increases the chances of a pocket of bleach releasing into your tank 8O 8O )