Paint over wallpaper or take it down.

Taking the wallpaper off  will be challenging so if the wallpaper was installed properly and is not coming off the wall leave it alone. Using oil-base Zinzzer primer or equivalent over the wallpaper then using Sheetrock mud any imperfections you don't want to see when the finish coat is dry. Now apply Zinzzer primer over mud then apply latex satin finish. Using paint with a higher sheen will show any and all of the imperfections in the substrate, so if you want to use anything other than satin skim coat the whole wall..