The Tree Wall Stickers that you put on your walls may have come from a large box home improvement store or from a specialty wall stickers store, but for the most part, interior wall stickers is interior wall stickers, and the quality was most likely good if you were also able to afford wall stickers.So, assuming the wall stickers is good, and that you were wall stickersing over another coat of wall stickers, and not new walls, which require a good primer coat before you wall stickers a finish coat, it is my hope that you cleaned the walls thoroughly with a trisodium phosphate solution. Trisodium phosphate, or TSP, is a wall and ceiling cleaning agent used by most professional wall stickersers and it will strip the dirt and grease off your interior walls and ceilings. Wall Stickers at beat quality at Cheap Wall Stickers