Easiest way to start plugin development?

Hi, I'm currently trying to get started on IDEA plugin development, but I find the documentation rather hard to come by. Does anyone have any tips about how to start?

I've downloaded the plugin-dev package, but I could use something simpler for examples, and a 1-2-3 guide about how to write a first plugin. I have seen something like this before, but now I can't find it.