We are surrounded by oak trees. We gather up the leaves and run them, along with the typical yard waste like fallen twigs, trim, etc., through the chipper and end up with a really nice mulch.
As I dig the hole, I pull out the big rocks. If the clay soil is really dry, I fill the hole with water and let it soak in. Once the hole is ready, I usually will put a mix of the leaf mulch, vermiculite, peat, potting mix with mycorrhizae in, nestle the plant in and finish filling it in. Then, another good watering followed by a top-dressing of pine bark mulch. Next thing you know, the earthworms have moved in and the plant is growing quite nicely.
The only thing that hasn't done well are our knock-out roses. That's more of a lack of sufficient sun issue though. (Now, if only we could convince the neighbor to take out that one itty-bitty 75-foot oak...)