Ask HN: Best way to get started with game design

I have a few ideas for basic games that I've been planning to build for a few years, but never had the time. I'm comfortable with the technical and graphical requirements needed to implement desktop and mobile games, but I'm interested in obtaining a more solid foundation in game design theory prior to starting. This is strictly for side projects at the moment and not a full-time venture. I've read many articles on game-play mechanics and found a few books on Amazon, but I've never actually built a game. I also found some good books (Game Design: Theory and Practice by Richard Rouse III; Art of Computer Game Design by Chris Crawford). Is it better to just jump in head first and start programming the game or should I get a stronger foundation in game design theory? I would be interested in some recommendations from fellow HN members that have more experience in this area.