Get your supplies for the job: hand masker, drop cloth, extension pole, screen, bucket with plastic liner, pole sander, roller frame, and roller. You'll need paint and latex extender (not shown.)
Put down some drop cloths.
Start masking off the woodwork using blue tape.
Here's how you mask the baseboards.
Sand the walls with 120 grit sandpaper.
To avoid paint bleeding through the tape and onto the baseboard below seal up the paint with a trim paint or clear shellac. Make sure the paint is dry before putting on the wall paint.
Use a hand masker to further extend the protection of the blue tape. This avoids paint splatters.
Remove the fibers from the roller using blue tape. The reason we do this is to prevent fibers from releasing onto the wall.
Put your paint into the bucket and reserve some for brushing out edges.
To get less brush marks add a couple ounces of latex extender to your paint.
Start brushing out the edges using a 2.5 inch brush. Make sure it's brushed out evenly.
Blue tape is kind of hard to apply on the top crown moldings so we're gonna freestyle with a steady hand. This takes practice.
Once the perimeter of the wall is brushed out we're ready to roll our wall.
Dip your roller generously and roll out excess paint on your roller screen. Then start painting. Work from left to right with the roller always starting in the center of the section where you began.
You're done with your first coat! Now repeat as needed. When the paint dries, usually 1-2 hours per coat for latex paint depending on temperature, you can remove the masking tape.