Mess up the default scripts and see what happens. Eventually you'll observe something interesting and you'll get an idea for a good feature. By doing this, there is more chance of doing something uncommon.
If you want to design a CMS, the first step is to understand how the scene system works. What is $scene? what is the "main" method and what's so special about? Then observe how things work in the "update" method. It's all simple really, it just builds on your basic condition clauses.
Finally, as Aqua stated, tweaking sprites is very interesting, at least for me. My first released script is based off sprites (Enhanced Battle Cursors). Well, that's just moving a sprite, but still. Try to make HUDs, they're rewarding. In the process, focus on learning how to do it right, instead of just doing it. That improves your knowledge and the script's performance.
All there is to say now is happy scripting ^_^