Creating new flower bed

Anyone have pointers for creating a new flowerbed in a yard that has a lot of clay?

I'm being given a lot of perennials. I'd like to spend some time this weekend creating an area for them, so that I have a place to do some fall planting once I get the plants.

I'm thinking that might be wise to either borrow/rent/purchase a rototiller, so that I can till in some organic matter into the clay. But I'm not exactly a gardening expert. (Apparently growing up in a rural area with parents who grew fabulous veggie and flower gardens didn't rub off on me at all. lol)