I live in NC and one corner of my yard can have totally dif soil properties than another corner, so I always start with a soil test. Most nurseries will do them for you. I use a kit and do my own and then take the results to a trusted nursery who advises me on what soil conditioners to add. Usually its a bag or 2 of permatill (I have dense claylike soil and it needs to be lightened up) some manure, fertilizer and compost or bark chips. Sand makes a good mix in too.
Our Home Depot rents equipment, and just last weekend I rented a small rototiller and chewed up a good space for another perennial garden. It was only $18/4hrs and well worth it for the effort it saved me. I chewed up the space down at least 10-12inches then I tilled in bags of manure, 10-10-10, compost and permatill.
I dont go in for alot of expenive garden tools altho they are hard to resist. I have 2 shovels and 2 good rakes(one of which is only 6"wide and great for reaching between plants) and I just use old spoons and cups from my kitchen for other uses.