Common Drywall Errors...and Fast, Simple Solutions

This doesn't sound bad, but it is. If you have two adjoining sheets of drywall that fit snugly side-by-side, you risk breaking off drywall in ways that you didn't imagine. Not only that, but you have to allow for expansion and contraction. "Gypsum expands and contracts?" you may say. No, but underlying wood does.

Fix: Be religious about keeping that 1/8" space between sheets. I've found that my drywall square is about 1/8" thick. Or just cut little pieces of wood to use as measurement guides.