Lay Cut Strips on the Floor
Once you've measured and cut the first strip—and you're positive it's the correct size—lay it flat out on the floor and measure the next strip. Make sure there is enough space at the top and bottom of the second strip that the patterns line up correctly. You can use a pencil to label the back of the wallpaper if you are preparing several strips at a time (the pencil markings won't disappear when the paper gets wet). Laying it all out on the floor is much easier than trying to do it on the walls.