How to prepair the ground for a new garden

[ducks4you]

Sounds like it will be a good spot, probably already pretty fertile. For one that big and this time of year, I'd probably go ahead and till it up and get a legume going on it, like clover (you're in a different zone than I am, so you'd do best to call your county ag extension agent for a recommendation of what to plant). Planting a cover crop will do two things for you--1)build up the tilth of the soil, and 2)keep the weeds out. You'll also want to get a soil test done (also via the ag extension) to see what amendments you might need.

ETA: and !

TOTALLY agree!! I move so MUCH horse and chicken manure and their soiled bedding that I never thought about soil fertility. I learned (watching University of IL's "Midwest Gardener" last night) that our soil is neutral to alkaline.
I'm really shocked. We live about 1 hour north of where the glaciers stopped. I have more or less 18" of topsoil on my five acres, but I THOUGHT it was rather acidic. But, I'll tell you, where I plant and don't amend--like where I had grass--with compost/manure, things DON'T grow that well.
Whenever I find clover now, I either let it stay in the bed where it is, or I pull it up and throw it below my crop.
Clover seed is far cheaper than alfalfa, and I don't think you could eat enough peas to justify a 1/2 acre's worth of starter crop. Plus, the clover will find a way to stick around for you.
My horses end up eating a LOT of clover later in the year, when it's drier. They become super-slobberers, and that's how I can tell.