I usually use a hoe and work in sections, but there are a few methods out there. I also work some organic matter into the soil as I turn it - composted leaves & kitchen waste, some ground up eggshells, etc.
One way to do it is to dig out a 1' wide section down your row, putting the dirt on a tarp for the time being, then working the next row by taking the next 1' of dirt and putting it into the spot where the first row of dirt is. When you get to the last row, you take the dirt from the tarp and fill it there. You can mix in your organic matter pretty easily this way too.
And there's lasagna gardening - I had a book on it (it's in storage.... like the rest of my useful stuff) but basically you take up 5" of dirt onto a tarp, then lay down layers of newspaper, composted leaves, kitchen compost, chicken/horse manure, and then put your dirt back on top. At the end of the growing season you mix it together and for the next season repeat.
And others use a tiller.