When I paint commercially I prefer not to use the blue 3M painters tape. For starters it is very expensive, nearly $7 per roll, and frankly I feel more "old school" when I paint without it. In my crazy head I like to think clients notice when I do not use tape and it comes out looking great, causing praise and admiration to flow like the mighty Monongahela. Seriously though, for jobs like this accent wall with a red next to a white wall and ceiling you'd be a fool not to use blue tape to ensure a perfect and clean edge when the two colors meet. Sure it would be sweet to puff my chest out and paint it freehand, but it would also be annoying to keep touch up the colors when one just crosses over to the other. On a tall wall such as this any veering off the straight line will show. Typically when you are painting a wall a dark color, it is recommended that you prime the wall in grey. Red and other dark colors can be difficult to cover in two coats over top of white or new drywall. However, if you use a grey primer it's a good bet that you'll have success with two coats of the dark over top. If you are simply painting drywall, the primer coat does not have to be actual primer. In cases like the grey on this wall, I took white (or any light colored paint) finish paint and added black paint until I reached my desired tone of grey. This may be the "Shades of Gray" that Jerry sang about, no, I doubt it. But it is always handy to keep a quart of black paint around to darken colors up.