I'd suggest the south moor for beginners. it is a little more pleasant to look at, the peaks are a little lower, and there are far more people on it, at any one time. All these things will help you.
Pack as light as you can, the worst element of the moors, is the unever "tussocks", which will test your legs. If you can keep to the well worn paths, it'll make life a lot easier.
As mentioned before, always plan your route, and leave a copy with at least two people/organisation.
O2 has the best signal on the moors, vodafone has the worst.
Work on an average of 1-2mph walking pace. I know the average walking pace is 4mph, but things are a little different on the moors, plus it's not a problem if you're slightly ahead of scedule.
Check your planned camping area
HERE (map is at bottom of page), as some areas will allow camping freely, others will require permission, and some are not allowed.
Also as Skate says, take a map and compass (two is always a safer bet). Keep track of where you are, and were you're going. As you walk the first km, make a note of how long it took you, that way you'll be able to work out where you are, from time/direction/distance covered (just incase you can't make out any landmarks).
The most important rule. don't feel you have to do all of it, if you don't feel up to it. That's what the escape routes are for. The whole idea is to enjoy yourself.
Adam