The best way to start a side project is to pick a tiny one to begin with. Think if you can do something in a weekend. It is important to train your brain into believing you are a doer and a finisher. In my experience, the worst thing you can do is dream up a huge scope, spend months building the project, lose momentum and motivation, get angry with yourself, and generally become miserable. I have been there, and it is not fun at all. Consider challenging yourself to come up with the tiniest fun idea to build in a few days. For inspiration, try producthunt.com. Good luck!
I am using a Trello board to organize my life. The flexibility to define lists freely and quickly add issues is a big win. The lists on my board are: Today's task list, Task list, Friends & Family, Project ideas, Client work.