It is also important to remember to mulch any bare soil. I realize tree roots need to breathe, but you can get big rough cut pieces that allow enough air to get to the roots. As you go out farther from the tree, you can put a little finer mulch on top if you think the rough cut larger pieces are not appealing to you. Do not go up to the trunk of the tree with the mulch, just begin it an inch or two out.
The best mulch to use is that from your own property, but if you do not have a wood chipper or want to rent one, there are great places to get bulk mulch.
Just be careful. I got some from a nursery once and it had a lot of trash in it. I like Soil Building Systems because I know how they run their facility and they are close to me. Look for a source close as possible and ask questions about how and where they get their mulch and what type of wood it is. Native hardwood is best. I like cedar a lot, too.
Just make sure you do not get too fine a mulch as it can actually create a barrier and prevent water from getting to the soil!

Also, native ornamental grasses have deep roots and allow water to get down deep into the ground.

Thank you for the .pdf! I look forward to applying the screwdriver test after deeply watering.

Not sure why this is in the lawn forum but I looked at the ISA website. I'm filing that information under my garden humor folder. According to the website there are less than a dozen ISA certified arborists in Texas. One of them is Davey. Davey hires hundreds if not thousands of people to hack on trees all over the country. They must have had to send someone to the ISA school so they could get government contracts. All I've ever seen them do is "dehorn" trees. The result is a tree that looks like this...



There is a name for such a method (Pollarding) but it results in a goofed up looking tree. What kind of arborist would do this to an oak tree?