In most cases, it is not recommended to wallpaper over existing wallpaper, as the success depends on the type of paper already on the wall. While you might be able to cover non-coated wallpaper, you should never apply new wallpaper over a vinyl-coated one, which is more common. Doing so can lead to poor adhesion, resulting in bubbles, imperfections, and peeling. It can also trap moisture, potentially causing hazardous mold growth between the layers.

Even if the existing wallpaper is suitable, experts recommend applying only one new layer. Adding multiple layers (more than two total) can cause significant adhesion problems, leading to warping and bubbling. For the best results, the recommended approach is to remove the old wallpaper and all paste residue before hanging the new paper. If you are unsure about your wallpaper type, consider consulting a professional.

Deciding between a lighter or darker accent wall depends on the effect you’re going for. Choosing an accent wall in a lighter color will make a room feel brighter and more spacious and complement rooms with less natural light. A darker accent wall will add drama and depth to a room and help make larger rooms feel more cozy and intimate.

Textured or patterned vinyl wallpaper designs are the best option for hiding imperfections. Embossed designs or faux finishes like brick, wood, or linen textures are especially effective at camouflaging dents, cracks, or uneven surfaces. Avoid smooth, shiny finishes, as they can highlight flaws rather than conceal them. 

If you prefer peel-and-stick to traditional wallpaper, you can skip the priming process. Many manufacturers don't require an additional primer if you’re installing peel-and-stick wallpaper to painted walls. However, if you’re applying peel-and-stick wallpaper to unfinished drywall, you’ll need to apply a primer first.