If long runs, you'll probably find it easier to concertina the paper when pasting, as you would when papering a ceiling. Measure down from ceiling both ends of wall, 1 inch short of width of paper-to allow for cut off. Snap a chalk line between these points. Check with spirit level that this line is level, adjust if not. Better to hang it level even if line of ceiling is off level, or will appear wonky from all angles. Hang first sheet, then continue down as normal. Old rule of papering vertically is to hang working away from light source i.e window. As hides joints better, joints don't cast shadows highlighting them. Hanging horizontally, light runs along joints, generally highlighting thier presence. Therefore butt papers as true to each other as you can. Luckily lines will naturally hide presence of joints. If you can see joints daytime, you'll probably find they disappear when lit from above by artificial light i.e lightbulb. As under those conditions, paper has been hung away from light source. good luck, twiglegs