I would say don't till any thing up, but instead lay card board and news paper several layer thick where you want the garden to be. start small first as you can always make it bigger each year till it is a good size for your family,preferably in bright sun, cover with horse,cow,alpaca or chicken manure, then cover that with leaves,grass clippings,straw, then cover that with a 3-4 inch layer of soil then cover that with wood chips, DO NOT TILL IT ALL IN! it doesn't work if you till it in. This is referred to as lasagna gardening,less work in the long run with more yield in a smaller area plus the cost savings of no tiller and no fuel and no spading or heavy digging.Then in spring just after your last frost march/april time frame rake back the wood chips down to the dirt in rows wide enough to plant any starts or seeds then cover the seed back up with dirt and wood chips and water till you see starts from the seeds then you shouldn't have to water much after that or at all. And each fall/winter you add more layers to the garden always covering this with wood chips over the top of any layers you add.