Hanging wallpaper, or vinyl in some cases, is one of those DIY jobs that make some DIYers cringe with nausea. Why? Not because of the smell of the wallpaper paste. Usually, it's from a past frustrating experience.
Getting a grip on this job is like learning to tape and float drywall. What it really takes is patience. The main points, which are outlined in detail in this article on properly hanging wallpaper are straightforward.
The problems that most people have are really easy to solve. For example, I can't tell you the number of comments I've gotten asking why the job got botched.
The Importance of Using a Plumb Bob
Me: "And what tool or method did you use to plumb the first drop?"
DIYer: "Tool?"
See where I'm going with this? If the first drop is off, even by 1/8" from top to bottom, you'll never recover if the paper you're working with has a pattern. If anything, it'll get worse as you go along.
Task Lighting and Level Viewing
More experience paper hangers develop almost what seems a sixth sense for lining up the pattern. But matching the pattern can be a challenge for novices. On many patterns, the repetitions are not so obvious, and in fact what you thought was correct alignment at first glance turns out not to be so.
It's a visual thing. The first trick is to have proper work lighting. Natural sunlight seems to work best for me. That's not always practical. On my contract jobs, this twin work light has been the best I've found. In fact, I use it in my home wood shop.
Secondly, you need to looking at the seam horizontally. So much can change when you look at an angle. It's a real sinking feeling to get a whole wall done, step back to admire it, and realize, holy flying crap! It looked good up close! What happened??
The moral of the story is: have patience, go slow, and step back and check your work often.