Map out the room
A. Use a roll to lay out the wall
Use a full roll of paper as a guide to lay out the room. Butt a roll into the corner where you plan to start, and make a pencil mark on the wall at the edge of the roll. Slide the roll down to that mark, and make another pencil mark at the other edge of the roll. Keep doing this until you know where every seam is going to fall. You may have to cut down the first panel to avoid hanging small strips (3 in. or less) near doors and corners.
B. Work away from the door you enter
Wallpaper seams on straight walls are butted, not overlapped, but seams are less visible if you place them at the point farthest from where the first panel was installed. Minimize the visibility of seams by starting in the area opposite the most-used entrance to the room.
C. Start with a plumb line
Don't assume the corner you're starting in is plumb. Use a level and draw a straight plumb line about 1/4 in. past where you want the first panel of paper to end. Take into account that inside corner seams need to be overlapped at least 1/8 in. For more information, see “Seam Inside Corners” below.
D. Hide the last seam
If you're hanging paper that has a repeatable pattern, the pattern on the last seam is not going to line up, so try to hide it in a low-visibility area. The corner just above the entry is usually the best spot.