The job of hanging drywall is relatively uncomplicated; it's the finishing of the drywall joints where people get a bit flummoxed. A finished wall shouldn't have visible nails or joints, but should be really smooth. It isn't as difficult as most people think; if you take your time and buy the proper materials, your drywall will look professionally finished. It is very important to buy the right tools, especially the dry walling knifes; don't try to get away with just using a 6-inch knife, it won't work for all the smoothing, and the finishing will not have the professional look you want.
Step 1 - Applying Tape and Compound
When choosing the drywall tape to use, there are a few choices. The best type to use is a fiberglass drywall tape with an adhesive backing. This type is the easiest to use, since the adhesive will hold the tape in place. Use can also use paper drywall tape, it doesn't have an adhesive, so it is a bit more difficult to handle.
The first thing, is to apply a light coat of compound into the indentation where the edges meet, use the 6-inch knife, then press the tape into the compound; smooth out the tape, moving away from the edge.
When you are taping corners, cut the tape, then fold it lengthwise. Apply your compound and press your tape into the corner. For outside corners that have been covered by metal, you will need to apply three coats of compound, each spreading out further than the last, feather out the edges; this will fill in the bumps.
Once you are done taping and compounding, it will need to dry overnight.
Step 2 - Applying Compound
After the first layer of compound has dried, you need to apply the second coat; use the 8-inch knife. Over all the joints spread a liberal amount of compound, spread it evenly to smooth out any bumps, feathering the edges. Make certain the edges of the compound are smooth. Give the compound overnight to dry.
To apply the last coat, use the largest knife. This is to be a thin coat, just to ensure there aren't any bumps left. Again, feather the edges and let the coat dry overnight.
Step 3 - Sanding
You have to block the doorways, to avoid dust flying out the door. For safety sake, wear a mask. With a sanding block, gently sand all the edges until they are smooth with the wall. After the sanding is complete, check your work for any areas that are not smooth and may need touch ups.
Before you do anything else to your walls, allow the compound a week to dry. When finishing your drywall joints, you don't want to rush the process. Take your time, allow all the drying times and when you are finished you will have a professional looking wall.