I've been collecting a bunch of wood from the beach near our house lately with the hopes of making some neat artwork or possibly furniture. Are there any special precautions, techniques, or considerations I need to keep in mind when working with driftwood?
This is quite a broad question. I've use wood I've picked up beachcombing many times, all of which could be classed generically as "driftwood" but it's far from uniform. Some was originally branches and other random bits of trees, some milled wood that got into the ocean somehow. On top of that the amount of time the wood spent in the water made a huge difference in its condition.
As a result, I've picked up pieces that don't appear to be much different to what I might expect if they'd never been in the ocean but only exposed to some rain and sunlight. Other stuff has broken down, from a little to a lot and the worst of it is soft enough you can break it apart with your fingers as most people have experienced once or twice when handling washed up wood on a beach.
So bottom line I don't think there are any specific techniques for dealing with driftwood, but rather for dealing with the wood in whatever condition it happens to be in.
The very soft stuff I don't bother with myself, although I see the potential for decorative pieces. This can be used without any modification other than maybe a wash down once you get it home so that it's a bit cleaner. It can also be stabilized or strengthened if desired using various commercial products (various wood hardeners) designed to introduce resins into the weakened wood structure which then harden and reinforce the soft, or 'punky', wood. For smaller pieces in particular they can have resin forcefully introduced (search term: resin impregnation), using vacuum or pressure. This can result in even very soft wood becoming hard and strong, but it changes its appearance quite significantly, to the point that some people think it looks like plastic or resin.
Same deal with glueing the wood or using mechanical fasteners. With wood in reasonably firm shape it won't react too differently to fresh wood, with very soft wood you often can't use conventional glue or screws because neither has anything strong to grab onto.
In terms of adding a protective coating to a project made from driftwood, some people are OK with using oils, shellac or regular varnish to finish the wood, accepting the colour change that occurs. Others prefer to keep the wood looking as much like it did on the beach, in which case a "water white" finish is called for; a common choice here is a matt waterbased poly. With luck the piece can look virtually unchanged while having a coating that protects it from getting grubby from dust and light handling.