Taping and Mudding Drywall
To do the job right, set the room temperature at least 65 degress with enough ventilation to assist in drying. Inspect the walls and ceiling(s) to see that the panels are adequately fastened, with countersunk screws. Screw heads that are not driven into studs should be removed. Any ragged edges of the cut drywall paper need to be cut clean with a sharp edge blade, thereby tapering the edge back.
Deformities in the drywall surface such as bulges, must be removed by cutting, and then patched and sanded smooth to match. View the surface closely for indentations, and push the minor ones back in with the corner of a drywall knife.
Tools needed for taping consist of a set of drywall knives, for beginners at the least - a 4" through 12" blade. Knives for corners are optional, however can help make the definitive edge while a curved trowel can be indispendible for tapering major joints. Add to this a 12" or 14" mudpan (plastic or metal) or a hawk, to spread from, a tape reel and tape folder for seams, and for making cuts, a utility knife.
Look closely at the butt seams. Make sure the joints are cleanly cut and have no rises. Which would cause additional feathering of the compound layers ( see drywall install layout).
Mix the mud with only lukeward water and a hand mixer or cut back on time and effort with a drill and 1/2" chucked paddle. You may wish to either bed the tape first before procuring the lightweight compound for topping, or figure the amounts from the 5 gallon container ( available in smaller boxes and gallon container quantities). Also, you may want to stay away from speed dry mixes until you have skills with standard compound.
Apply the mixed compound onto the wall joint with a 4" knife, which fills conveniently over the tapered sections. Then apply the tape, while maintaining an obstructed path between your tape and the knife and setting the tape relatively tight and without bends or folds. Pushing a bit of the compound out from beneath the tape as you go. And when the strip of tape is embedded, take passes with your knife to tidy up across the surface, remembering that any unwanted excess from this phase that cannot be lightly scraped off, will need to be sanded.
While some experienced tapers bypass this next step -- you should let the mudd dry, and scrape off any high spots while not damaging the tape surface -- apply another coat of mudd with the next width of knife. Then let this dry as well, scrape to a smoother level and reapply a final coat of topping compound
Hit the screw head recesses with single passes of a narrow knife, grouping the heads in lines. Under most circumstances these will be one over with a second pass.
When all is dry, you are ready for sanding.