I prefer an organic mulch. In Georgia that is usually pine straw, shredded pine bark or pine bark nuggets, shredded hardwood mulch. I'd use about 3 inches worth, careful not to have it directly touch the trunk of the tree. Spread it at least out to the drip line. This link has a couple good pictures, one that is a bad example (mulch volcano) and one that is a good example.

Here is a link that might be useful: Good examples here

Thank you so much, this is exactly what I needed.

Arborist wood chips.

Wood is better aged, and unless you have room, and the equipment/time/strength to turn it now and again, fresh wood chips are better left to the pros. You CAN let a pile sit for a year or two, but it is better turned at least once - more is better. Until the pile has begun to break down, it needs nitrogen, it needs air, it gets hot, and can be acidic. Once the wood is well aged, then the need for the above is diminished, and it is much less acidic. As well, there will be a fair few large chunks of wood - so aesthetics comes in too. The bright, fresh-cut wood color disappears in a few weeks.

That said, I do know people who have been using fresh wood chips for years, seemingly with no problems. The one time I tried it, my plants didn't seem to do as well, so I didn't use it again fresh. I will admit that the price is very right - they are usually glad to dump it for you - and not have to pay land-fill fees!