If you become less of a risk, you increase your chances of getting cheaper contents insurance.
One way to do this is to make sure your home is secure, whether that's by upgrading the lock on the main door to your home, or fitting a lock to your 'self-contained' room, or both.
Without an approved lock, it's difficult to find a policy giving you theft cover. So know your locks.
Keep all your contents in your locked room. Anything left in a communal area is unlikely to be insured against theft. Remember, cover for theft only applies when there's violent and/or forced entry.