Just moved to a room where 3 of the walls are almost completely painted over in an "artistic" manner. I scraped down the high spots; don't really want to (or think it's worth it) to sand and clean up and then maybe skim coat. Unfortunately I've always tried to steer clear of painting and as such am a bit lost. Not sure what primer/paint will be most compatible and/or which would conceal the previous colors best. Any advice? Thinking a pale blue for the top coat.
The key to making this art go away and stay away is using the best primer for the job, and for this job shellac based primer is the only way to go. This is a primer made of shellac and a white pigment with alcohol as the solvent. It's thin and it goes on quickly by brush or roller, it dries in just a few minutes and you can do a second coat of the primer if necessary as soon as the first coat dries. Then finish with the latex paint of your choice.
I've used shellac based primer to defeat gold-colored roller stencil work that made a green stain through any paint that covered it. (One primer coat and done.) I've used it to cover gigantic five-pointed red and blue stars on white walls. (One and done.) I think you'll be very happy with the results on these walls.