Avoid leaving your bike where a thief can make assumptions about how long you're going to spend inside, e.g. at a cinema or a pub. Avoid leaving it where it is not overlooked from windows or seen by passers-by. You will get a feeling for the quality of a location after a while. Always lock it well, ideally with two different locks. Choose a bike that looks easily recognisable--thieves will go for such bikes less eagerly. Look out for telltale signs of theft of parts (stripped-down abandoned frames). Don't use quick releases--absolutely pointless if you're not in a race. Use rare locking mechanisms like five-point 'Allen key' nuts everywhere. Don't panic--be prepared.
Avoid leaving your bike where a thief can make assumptions about how long you're going to spend inside, e.g. at a cinema or a pub. Avoid leaving it where it is not overlooked from windows or seen by passers-by. You will get a feeling for the quality of a location after a while. Always lock it well, ideally with two different locks. Choose a bike that looks easily recognisable--thieves will go for such bikes less eagerly. Look out for telltale signs of theft of parts (stripped-down abandoned frames). Don't use quick releases--absolutely pointless if you're not in a race. Use rare locking mechanisms like five-point 'Allen key' nuts everywhere. Don't panic--be prepared.