Step 5: Attach self-adhesive wallpaper
When you apply the adhesive wallpaper, start from one corner; press your hand in diagonal direction gradually removing the paper substrate. If there are some air “bubbles” under the wallpaper, remove them making holes with a pin near a “bubble” edge to let the air out. If you have to attach a number of overlapping wallpaper sheets, the edge of the upper sheet must look in the direction of the light (window), or else it will cast a shadow.
And of course, do it together with somebody!