Step One: Watch Mary Rose Cook Live Codes Space Invaders from Front-Trends. (The second worst conference name ever?)
Step Two: Fork this gist.
Step Three: Respond to this question in your fork: What is one approach you can take from this Mary's code and implement in your project?
Step Four: Totally Optional: take a look at some of the other forks and comment if the spirit moves you.
Having a single collection of objects to be updated all together for the purposes of position and collision. Also, like, everything else.