Photo by dpwk on Flickr.
Bike theft is unfortunately common. No bike can be fully theft proof, but we can do several things to make stealing it more difficult and riskier to the thief. Other things you can do will increase your likelihood of getting your bike back like I did. There are no guarantees, and you need a little luck, but here's how you can maximize your chance of getting lucky.
To reduce the risk of theft, make sure you use a good lock, secure the various parts of your bike together, and lock up to a good rack or alternative object. Personally, I am partial to using locking skewers to protect my seat and wheels, locking my frame directly to some immoveable metal (lesson learned!), using a solid u-lock, and parking in strategic locations.