I had my plot (which was just rough grass) ploughed by the local farmer (I had sprayed the grass with Roundup to kill it - probably not really an option this time of the year, but a plough would "bury" that anyway), then I hired a mini-tractor and powered (i.e. PTO) rotavator which converted it into very workable soil for the first season.
I made "lazy-beds" by just piling the soil from where I wanted the paths (about 18" wide) onto the area for beds (4' wide). Avoids the cost of wood to retain the raised beds, but of course some soil falls back down on to the path when you work it.
I put weed suppressing membrane on the paths, and some sawdust / wood chippings from tree clearance onto the paths.
Some pictures in my blog if you have time to kill ...
I have taken a hay crop (well, I cut it in late June and rake it up!!) and piled it to rot for a year or so to increase the amount of compost I can make. I have also had a huge pile of manure from the local farmer each year (stacked until well rotted)
Well rotted manure, spent mushroom compost or spent hops would help (but don't put it on the zone you want to use for Carrots / Parsnips etc.)
I recommend you grow what you like to eat. No sense growing a bunch of stuff that a) may not grow that well plus b) you don't really like it anyway! - all too demoralising.
I have read of many people getting a plot going by making planting holes (with plenty of compost / manure), marking with a stick, covering the lot with weed suppressing fabric, and planting Squash in the holes. They can be about 6' apart. Makes for an easy first-year start, and the weeds are pretty much killed by the end of the first year.
With a large area you would have room for soft fruit too - e.g. Raspberries, Currants, Black berries, Gooseberries ... and some cordons of Apples etc perhaps?
Do you have rabbits? If so I recommend that you net the perimeter; it is soul destroying if they eat your hard work
I have split my area into two separate rotation zones. 4 beds in area one for normal 4-year rotation (Peas/Beans, Brussels/Cabbage, Roots, Onions/Leeks) and the other area for Potatoes, Strawberries, Overspill Brussels/Cabbage, Sweet corn and cut flowers - Sweet peas, Gladioli )
I have a spreadsheet of vegetable varieties and sowing times etc if you are interested:
http://chat.allotment-garden.org/index.php?topic=34306.msg411041#msg411041and there is a chart here:
http://www.allotment-garden.org/vegetable/general/sowing-harvest-vegetable-chart.php