I made a staff I just found a good stick in the woods and carved it for two or three days. I carved two spirit animals in it the owl for wisdom and the bear for strength. But then my brother broke it in half the same week I carved it.
When i make one it's typicaly because a suitable staff has come to me to replace the one i already have. The stick will find you, i think this may be important. A good stick is the shape you like (irregular or straight) and very sturdy, robust even. Not too heavy either, you don't want to be lugging a log around.
As said above carving can be used to decorate, as well as charms, fabrics, stones, feathers, etc.
Keep sound intention, and keep an eye out for fallen or dead wood.
Also, when you come across the wood that just feels right, you should only do to it what feels right to do. My wife makes staves with elaborate connections between the stones she places in carved niches, and lacquers the whole thing. A friend of mine simply stripped the bark and sanded his staff, no designs, no stones, etc. and it worked for him. Mine is simple as well, shaved and sanded, with carved runes, and that's it. Just do what feels right.