Done a few of these Here's an example:

When I got my current house a few years ago the driveway was real soft. Who ever put it in forgot the base. I ended up digging it up and scraping it down about 1 foot. I filled it back up with about 8-10 inches of 2" limestone, drove on it for about a month and then topped it with about 2-3" of road bond. I'm in a "soft" area and lets just say even with going in and out with the service truck and various small excavation equipment the driveway no longer moves.

Now different areas call for different methods but I'd seriously pass on tilling your base of clay or what ever you get into because it's already packed my mother nature. When you till something up it's real difficult to pack it back in as good as when it came out unless you have some serious equipment. Trust me on this, I've been digging in underground lines for over 10 years now. Right now is a great time to do this project and if you can stage the project out so you actually run on your base layer for a few weeks you'll be in real good shape.

My absolute best advice though is to drive around new construction and see what is working in your area. It's the only way a backyarder is going to see what works for your place. I'm surprised that anyone would give advice on something like this without this same warning. Even my advice that works like gold in my area might be junk for you. Surface materials very greatly around the county so take the trip and see what's going on out in your parts. Also FYI, unless you see the fabric being used in residential around you I'd pass on it.