The first step in discouraging bike thieves is to lock your bike correctly with proper equipment.
Recommended Security Equipment
Hardened U-Shaped Shackle Lock - Be sure to use a hardened U-Lock to lock your bike. Make sure the lock is secured snug between an object and your bike to minimize slack. Excess open space gives thieves increased leverage when breaking a lock with an item like a crowbar. Using an additional cable to run through the wheels and back to the U-Lock is recommended.
Locking skewers - Skewers that lock the wheels to the frame in place of a quick release skewer are recommended to prevent bicycle wheels from being stolen. Seat leash - a seat leash is a great security measure to utilize to reduce the likelihood of a thief taking your seat and seat post. Quick release seat clamps can also be converted to locking clamps.
Be extra sure to remove all additional accessories on your bike (computer, lights, panniers and baskets) and take them with.