I like to use painters caulk and tape. Its a trick a painter taught me. Apply a small bead on the side to be painted and wipe it smooth against the tape with your finger. This will block paint bleed through while you paint. Smooth your paint out on the line and let it tack up for a half an hour or so but don't let it dry all the way. Pull your tape and the caulk and paint line should be sharp as a razor. Do one wall at a time so the caulk doesn't seal the tape to the wall. This works well on heavy orange peel and knock down textures.