Inky, I learned by viewing other people's scripts. I actually started by using TrivBot and deciding that I wanted it to do some things differently. So I used the mIRC help file and asked questions here and in #scripting channels as I worked out how to get things done.
Keep in mind that I have a lot of programming experience in other languages already, so this wasn't that hard to learn for the basics and the help file is really great if you have an idea of what you are looking for.
Whenever I wanted to try something new, I usually got someone else's script that did what I wanted to try and saw how it worked and then played around with it until it did what I wanted it to. Sometimes, I just learned by the help file, of course.
The best thing you can do is to learn to use ECHOs to troubleshoot. If something isn't working, try inserting an echo at different points in the script to echo out "testing" or a variable or whatever else so that you can figure out where the script is failing.
