I have started many side-projects but left them half way, because i got bored or something else caught my eye. But with my latest project[0] I am following a simple philosophy by John Resig, "Write code every day"[1]. Even if i write code for 30 mins, it's okay. By following this i am always in touch with the project. It has helped me a lot in being disciplined.
[0]: https://github.com/smurfpandey/mysqlweb
[1]: http://ejohn.org/blog/write-code-every-day/