I'm new to wallpapering, and am looking for advice to how best line a bedroom with paper. One wall is going to be a feature wall with wallpaper, so I plan to line this wall horizontally. The other three walls will be painted, so I intend to line these vertically. My question is what to do with the internal corners. I've seen some YouTube videos of decorators cutting the lining paper into the corner and butting up the two papers, and some that slightly overhang the corner by 5mm. Which method is better? Also, if I do overhang the lining paper by 5mm over the corner, does the next piece of lining paper butt up to it, or do I overlap that with the first piece, then cut through both pieces (like you do with patterned wallpaper)? Thanks for your help.