Before papering a wall, test whether it needs to be sized by moistening a finger and pressing it on the wall. If the mark disappears quickly, the wall surface is hot and size should be applied to it. The reason for applying size is to prevent the wall absorbing the water from the paste too quickly, thus stopping the paper sticking properly. It should always be applied to newly plastered walls before papering.
Supporting the paper when papering ceilings
Use a length of batten at least 50mm, 2in wider than the paper to take the weight of the folded paper while the paper already in position is being brushed down. To make it easier to hold, attach a short rod of at least 25 mm 1in diameter as a handle.