Depending on a few factors, clay can be VERY nutritious stuff. Among the top problems gardeners find with it are a lack of: friability; oxygen; and organic matter. Your specific clay may be great, and it may be horrendous lol.

As many people will also, I suggest your fist step is to call, or go online to find, your local county agriculture extension. Ask about a soil test. In most parts of the country they are very cheap and will offer you specific help. Your county agent can also help you with background on what other people in your area have chosen.

That said... clay soils often benefit from very healthy additions of organic matter of various types. The more varied, the better. This though is where a soil test can help you decide which are best for your instance.

Also... try posting your question in the Soil, Compost and Mulch forum.

I garden directly into my red clay soil and have never had a better garden location. I tilled in a large amount of wood chips the first year (10 years ago) but never since. I mulch regularly with an assortment of things and that's it.

Red clay soils are some of the best in the world, in terms of agricultural production. Mine drains well, in spite of the fact that it seems like the stuff that bricks are made of. My husband asked me if I wanted raised beds and I absolutely refused!

I have orange red clay as well and totally understand how hard it is to garden in that stuff. Do not add peat moss. But lots and lots of organic matter is the way to go. We trench compost and in the area we are doing this we are starting to see good results. Organic matter is truly the only good answer. We also have piled up wood chip mulch in areas and when we moved it 6 months or so later, we could see that the top inch or so was starting to change. What ever you do, it will be a long slow process.