My plan currently consists of a vision of the type of game I want, and not much else. This has got me much further than the previous 50 grand schemes of world domination
I once had a great plan for an RPG that consisted of more than 1mb of pure text. All of the features were pies-in-the-sky though. No RAD could ever have done THAT.
I keep a "to do" list but most importantly a "done" list, for motivational purposes
It was suggested to me recently and I love it. Periodically I take some items out of the "to do" box and into the "maybe" pile; things that seemed nice at the time but now have grown old and I don't feel like implementing them.
This is all for fun so most of what I do, I do it for the fun of it -- the journey matters, not the end result. The main criteria for selecting the next thing to do is how easy it is to implement and how fun I think it is for me to code. And so I've been ticking items off my to do list like crazy.
A great factor here are the tools I use. Dev in Python is waaay more rapid than in Java, which in turn is moderately more rapid than in C++. RAD methodologies can only get you so far. In Python I can pass lists and dictionaries all over the place without breaking a sweat. And then there's the doryen RL library, which has easy true-color console display capabilities and every RL algorithm you could possibly want. A powerful combination.
So, as you can see, we all know how to pump code like crazy. It's just that, contrary to intuition, RL dev is pretty hard for a one-man army.