If your walls are already painted in a latex paint (not primer) that has dried for at least 21 days, you can hang your wallpaper mural over top.  If you need to paint your wall, you can use a latex paint in an eggshell, pearl or semi-gloss finish (allow to dry for 21 days), an oil- or alkyd-based primer (allow to dry for 3 days) or Zinsser BIN Lacquer Sealer (allow to dry for one hour).  We do not advise hanging over regular latex primer as it will be difficult to “slide” your prepasted wallpaper on the wall and the primer may chip off underneath your wallpaper.