The prep work for concrete goes as follows:
Shoot your elevations with a transit. Pound in a benchmark stake somewhere out of the way, but where you can see it with the transit, and mark it with your elevations ...grade, gravel line, sand line, and finished floor (this is in case you need to move your transit, or it gets bumped) .You can rent a transit at an equipment rental place, or buy one ...a decent basic transit can be purchased new for $200 or so.
Dig down to hard pack soil as a base, or compact your fill with a tamper or plate vibrator, whichever applies.
Set up your form boards, checking them with the transit. Use masons line to string line them straight. Add some slope if its outdoors (or indoors if you like) ...1/16" - 1/8" per lineal foot is sufficient. Brace the hell out of the forms with stakes, one every 2 - 3 feet minimum is needed to assure that the forms don't bow or blow out. The more the better. Each stake holding the forms should have a 45 degree diagonal stake. Check the entire perimeter of the forms with the transit to assure they are accurate ...adjusting as needed (it doesn't hurt to leave them 1/8" or 1/4" high until you're done with the sitework ..gravel, sand, rebar, etc ...then tap them down ..this prevents the forms from getting knocked too low during the site prep.)
If you're pouring up to an existing vertical surface, such as a wall, then snap chalk lines for each level ...finished floor, sand, gravel, grade. This will let you know exactly where you are when doing each stage of the site work, as opposed to measuring down from the finished floor line all the time.
Use asphalt impregnated expansion board against such surfaces, and between the sections of a larger slab. It also doesn't hurt to attach a 2x4 against any vertical surface for the screed board to ride on. Attach it with the bottom flush with the finished floor line of the concrete, and the screed board gets 'ears' put on it to enable it to ride on this board.
Fill with 4" - 6" compacted gravel base, then vapor barrier, then 3" - 4" sand. Anything going under the slab such as plumbing/electrical lines is installed in the sand layer. Wrap all under slab pipes in batt insulation if they aren't completely covered by the sand, and tape with duct tape ...especially where they come up thru the slab. This prevents the concrete from touching and eventually breaking the lines. If you're putting in a toilet or other drain, then build a small box form the thickness of the slab to surround the line where it comes to the surface and backfill it with sand.
Next goes any reinforcing such as rebar/wire mesh. Use the little adobe blocks to hold the rebar up out of the sand.
Just prior to pouring, hose down the entire works. As someone else said, this keeps the moisture from being sucked out of the concrete too fast.
Use a long straight piece of 2x4 or 2x6 as a screed board to initially level the concrete as you pour, using the tops of the forms as a guide. It helps to cut off the tops of the support stakes prior to pouring so they don't interfere with the screed board. If your slab is too wide for the screed board to reach across, then you need to install a temporary screed form at midspan. Metal stakes work great for these. If it's a big slab you should be pouring it in sections anyways ...alternating sections on separate days. And don't forget the asphalt impregnated expansion board between sections ...1/2" thickness works fine.
Pull the wire mesh up off the sand and into the lower 1/3rd to middle of the concrete as you pour, making sure it stays well below the surface. Work the screed board back and forth, filling in or removing concrete with a shovel as you go. It helps to have at least three people doing this ...one on each end of the screed board, and a third person working the shovel. Yank any midspan screed forms as you go
After screeding, you'll use a bull float on a long pole to smooth the cement. As it dries you'll use the finishing floats. Do the edges by hand with hand trowels. As it hardens you can get out on it and work it by hand using knee boards to work off of.
When you're satisfied with it, then give it the final finish ...broom finish, whatever ...and spray it with a hardener if you like.
That's pretty much all there is to it ...the majority of the job is in the prep work. You work fast when pouring ...then sit around for hours and babysit the slab as it hardens, periodically finishing it. At this point you should have some beer handy, as it's boring as hell.
). Really takes experience to be real good at it. If you've got a buddy with some experience pouring concrete, I'd suggest buying a few extra beers and getting him to help 
I will add some more reinforcements tomorrow as it makes good sense guess you can never have enough when it comes to concrete. The plot I choose was very level as it only sloped 1" from front to back and 1" from side to side. I live in the bottom of a valley so under neath 2" of topsoil is a layer of hardpack rock and clay. It makes a great base for foundations but it makes growing a garden suck. I got the forms in today and the gravel in place. I am planning a pour on Saturday so I can get as many family members as I can find to help. We will see how it goes. With the advice I have and the help it should go fine. Come to think of it I am probably alot stronger than I am smart so it should be a peice of cake! 
