A common mistake is to cut off too much of the caulk tube tip, leaving a hole that's way too big for most interior caulking work. When you're filling small cracks to prepare for painting, cut the tip carefully to keep the hole tiny—about 1/16 in. in diameter. The tiny hole lets out just enough caulk to fill typical small- to medium-size cracks. For larger cracks, make a second pass or keep a second caulk gun on hand, loaded with a tube that has a slightly bigger hole. Keep the caulk gun moving quickly along the crack as you squeeze the trigger. This, combined with the small opening in the tip, will give you a nice caulk joint that needs very little cleanup. A quick swipe with a dampened fingertip will leave a paint-ready joint.