I'm far from a DIY expert but I've wallpapered a couple of times and will be doing some more in a few weeks. It's like any skill really - the more you do, the better you get.
I was taught by my Dad & Grandad how to do it and the main tips they taught me were:
- Use plenty of paste to stick the paper to the wall to reduce the chance of any peeling. More than you might think but once it's up and you're happy, wipe off the excess. Go right over the edges of the paper with plenty of paste when it's on the table. Don't fret if some goes on the front of the paper occasionally - just make sure you wipe it off when the paper is up and you're happy with the positioning.
- Use good quality lining paper and put it up horizontally rather than vertically to improve the finish.
- If you're not happy with how a piece of paper is going up, take it off, repaste and start again. Don't carry on if it's not working. It's amazing how stopping for a few minutes and repasting before trying again will make things easier second time round.
- The paste will hold the paper to the wall while you adjust it for lining up and trimming of edges round windows/doors etc. for a good while longer than you'd expect before drying and really 'sticking' to the wall. You're not on a strict deadline of getting everything lined up and sorted within 30 seconds before it sets solid so take the time to get it right. (Yes that sounds obvious but I was terrified of it drying to quickly the first few times I tried)
- Don't push the seams of the paper together too much when lining them up on the wall - they may raise slightly. Aim to get them as close as you can next to each other, without overlapping.
Another thing to consider is what's on the one small wall you want to paper. Is it a flat wall with no features? Or is there something like a chimney breast or alcoves you'll be working with? Most of the time, it's worth getting something to act as a plumb bob and using that to make sure the first piece of paper is dead straight, but if your house is a bit older and more prone to wonky walls, then it might look better to line up the paper with the edge of that 'feature' if it's not too far out from being centre.
Also, how flat is the wall you're papering? If you can, sand out any uneven surfaces as much as possible - good quality lining paper will help cover some of these imperfections though.
Finally, how tolerant are you of little mistakes? Would you be happy if there was a bit of paper that didn't quite match that no-one else could spot, but you could see all the time? I papered my alcoves in the front room and because of said wonky chimney breast wall, there's actually a tiny gap between the paper and painted wall that gets slightly bigger as you look down towards the floor. No-one else has noticed it (or said to me anyway), and I know it's there but don't care enough to worry about it. You may not be so forgiving with yourself though - only you know that.
Try watching some DIY tip videos on YouTube too and see if it looks like the thing your existing DIY skills would match with.
If you're still not sure then I'd say try anyway - if you like it and are happy with the result then great! If not, at least you know for future DIY projects and can pay for someone to come in and do it for you but at least you've got the experience to know for next time. You don't lose really.
(Apologies if any of this sounded patronising!)