You can get a really long way by trying (and failing!) to write scripts of your own. This kind of stuff is much better learned by doing, rather than through lessons, guides or videos. Think of a cool script that you want to write, make sure it is simple, and give it a shot! Good examples of simple scripts are those which have a very basic task which can be gradually expanded. For example, a woodcutting script can start by just clicking on trees. Then, you can add appropriate delays and pauses, dropping, walking, banking, upgrading axes, etc etc.
As always, if you have any questions, post em here and i'll do my best to answer!
-Apa