You have to print them with a laser printer, so the glue doesn't dissolve the ink. and don't forget to add an over margin (I don't know if this is correct in english ... ^^') so you can have a margin of error when you glue the sheets of paper next to each other.
Ah. But wouldn't some sides of the paper have their margins cut off? Depending on what order you place them on the wall. Otherwise there'd be white lines dividing up the whole piece. I think I am getting it... lol