This might sound obvious, but the most important thing when choosing a wallpaper is that you love it!
Also, before doing the whole place, start by applying it to a room you don’t spend most of the time in, as a trial. It is important you make sure you are going to like it for a larger or more frequented area of your home.
Make sure the walls are ready. Fix any cracks or irregularities on them, before starting the project.
For more tips on wallpaper selection and how to apply it like a pro, visit How to plan a wallpaper project — and pro tips for applying it.