How to Lock-up
Use a U-lock and lock your bike to a bike rack to keep it safe. A smaller lock is better because it gives thieves less room for a leverage-based attack. It is also helpful to have more than one locking method to prevent theft.
At a minimum, you should lock your bike wheel and frame to the bike rack to prevent theft. Consider locking your front wheel and taking your seat with you for more security.
A bicycle with bolted seats and wheels is better than the quick-release variants as it adds an additional layer of security, discouraging would-be thieves. Please do not leave your bike outside without a lock, as it will most likely be stolen quickly.