Many will dread inside drywall corners because of the angle and difficulty of imbedding the tape. Or, perhaps some have unsuccessfully tried to use paper-covered metal inside corner bead. Or they have tried to use mesh tape without much luck. First of all realize that your walls are rarely straight enough at the corners to use the metal corner bead without it popping off, so forget the metal paper-covered corner bead. With the mesh tape, it is just too easy to snag that mesh when over-coating – been there and done that. So this leaves the last option, paper tape.
Imbedding the Tape
What you need to do to imbed the tape is measure and pre-cut your tape and have a bucket of water ready. Then place a coat of drywall compound on the corner that extends a little farther than your tape. Quickly pass your tape through the bucket of water, shake off extra water, and adhere it in place on to the compound. Then using a 5″ taping knife, use your knife to press down each side of the tape at the corner (one side at a time) and while doing this squeezing out the excess compound, only leaving a light coat under the tape. Let this dry. Now, take a look at the graphic below to get an idea of the steps needed to finish this corner.
Overview of the Coats
After each step, you will allow the compound to dry completely and then scrape down any bumps that stick up. You want a level surface before putting on the next coat. Do NOT sand until all coats have been put on, and then only sand lightly right before priming and painting.
This post gives a good summary, but for a better overview and a video, see my tutorial for insides drywall corners at http://www.drywallinfo.com/insidecorners.html