Before you begin slapping up huge sheets of drywall, you will want to make sure that the frame upon which it is to hang is properly prepared. Ideally the wall will have been built 16-inch on center or some other number evenly divided into 48 inches. This will prevent the necessity for cutting every sheet of drywall to length, thus saving waste and man-hours. (16-inch on center means that the frame is built so that there is at least a stud every 16 inches.)
Of course there should be no uneven surfaces or old nails sticking out of the wood. If I am re-doing a section of wall where I have torn off old drywall, to repair water damage for example, I will run the flat top of a hammer up and down the face of the entire exposed frame, just to be sure that there are no old nails or staples that I missed.
It may seem obvious, but you would be surprised how often it is neglected. You will want to be certain that anything that is supposed to be inside the wall, is inside the wall before you begin. Make sure especially that insulation, plumbing and electrical wires are properly run and secured. If you have more than one person working on a project it is important to coordinate this aspect. Electrical boxes generally should extent beyond the frame by about 1/2-inch in order to make sure the box is flush with the outside of the final wall.
The opposite is also true. You must make sure that you do not leave some important (or even unimportant item) inside the wall. I have torn down old walls and found all manner of things inside, shoe grease, tools, a newspaper and once even a wallet. I am sure the fellow who left it behind was suspicious of his fellow workers for a long time after. Luckily (for him) there were only a few dollars inside.