Work in 3-foot by 3-foot sections, guiding the sander horizontally across each board, in line with the wood grain. Start with coarse 60-grit paper and then follow-up with finer 100-grit paper to remove abrasion marks. The final light sanding is often easiest to do by hand.
There are a few other extra details that factor into your final interior painting cost including: Higher quality paint products or designer paints increase your cost Painting walls with a lot of doors and windows can decrease costs Drastic color changes may require expensive extra coats for proper coverage Adding an accent wall increases cost/complexity as well

Another tip! If you’re painting textured walls, even edge lock tape won’t always do the trick! You can put the tape on the wall and then go over the edges with a thin stripe or PAINTABLE clear caulking! One part will come up with the tape, the other stays on the wall under the paint, and keeps the paint from seeping under the edge of the tape. Just remember to keep it thin so you don’t see it on the wall! Hazel February 25, 2015
There are a few other extra details that factor into your final interior painting cost including: Higher quality paint products or designer paints increase your cost Painting walls with a lot of doors and windows can decrease costs Drastic color changes may require expensive extra coats for proper coverage Adding an accent wall increases cost/complexity as well