If it has been cleaned adequately, plop it in the tank. If it is a bit "raw" you should be able to boil it a bit to kill anything that has grown on the wood. If you are concerned about the bit of color it will add to your tank, you could soak it for a while until you no longer see the color leaching out of the wood. The trouble with trying to get all the tannins out is that it could take from a week to a tear to be happy with the amount leaching out. The week isn't too bad but some wood will take a very long time.
I'm trying a method I read about from a few different sources on the internet. I can't remember the sites, but I know not everything you read online is accurate.
I'm going to boil for 15 minutes, dump the tannin-soaked water, and repeat 2 times.
It'll take a long time for the wood to stop releasing tannins although the amount of tannins released diminish over time. There's nothing wrong with tannins leaching in tanks.
I prefer the tannin look personally. You can boil the driftwood and add it to your tank. Water changes will lessen the appearance or you could run a good quality carbon to remove teh discoloration.
I've never had to deal with that. I've either had a tank I didn't mind having the tannis in (it can look cool) or I wind up buying pieces that are already submerged in my lfs's tanks ... yea, they often say they're not for sale but, really, they are.
Once you boiled it a few times. You can see how much tannins are released into the pot your boiling it in. The water in your tank will not get yellow looking over night. It will take a while to get a "dirty" looking color, and if you do your regular weekly partial water changes I doubt the slight tinge will be all that noticeable. You can use carbon in your filter to help absorb the slight discoloration also.