Step One -
Purchase a decent D-Lock or Two, a high quality chain lock and an krypton extension cable. At the very least a D-lock that is branded.
I also have a second D-Lock and Chain Lock if the environment is 'dodgy'.
The following site may assist
Step Two -
Invest in security tagging usually allowing you to chemically mark the frame with a unique identifier which is registered on a national database tied in with the police. Electronic devices also exist. Check with your local police force as they may do this for free.
an example would be https://www.immobilise.com/view.php?stage=category or http://www.evanscycles.com/products/datatag/electronic-security-system-ec011452
Also photograph your bike and any identifiable marks including the frame number and wheel serial numbers if present. Also obtaining a UV marker pen and decorating the frame or other key parts will come in useful when tracking components as the markings can only be seen by a UV light which most police forces have.
Step Three -
Get insured,you can add a bike to a property insurance policy but chances are your bike is more likely to be stolen than your house (Lift with the knees and not the back). Cycle specific insurance exists not only for the bike when it is correctly secured using appropriate locks for the bikes value but it also insures the rider regarding public liability or being hit by an uninsured driver, cyclist or low flying pigeon. This may seem odd (not the pigeon) but this does help as it counts towards the character of the rider. Some policies also do a recovery service. I suggest looking at the following website
This may seem excessive but i do not drive, i have cycled since i was 5 and seriously when i was 12. I have had multiple theft attempts mostly when on the bike including at knife point (they failed).
The police will do what they can as they really do like arresting people if the evidence is available and they also like breaking doors down and they do recover a hefty amount of bikes as most stations i have seen have racks of recovered bikes. If they cannot find the owner they cannot return the item. Adequate locks will only slow the individual down or deter them from trying but we need to take steps that law enforcement can identify the owner and return the item.
That said there has also be an increase in riders with expensive bikes being followed home from trails and have bikes stolen from homes with poor storage like sheds or garages make sure the bike is securely stored at home as some locations may not meet insurance policy requirements.
One of the items I tend to do is remove the seat and post when the bike is locked up, it may not prevent the bike being stolen but it it will make it far more uncomfortable to steal.