Theft is most often a crime of opportunity. If your vehicle looks easy to break into or steal, thieves will be more likely to act on their instinct. There is no sure way to prevent your vehicle from being broken into, but there are ways to decrease your risks significantly.
When parking your vehicle remember to stay in a well-lit area and near lots a people.
Place personal belongings out of sight inside the passenger area of your vehicle or place in the trunk.
Keep vehicles locked with the windows rolled all the way up.
Install a car alarm system. Most pedestrians will turn and look when hearing the audible alarm activate. Thieves do not like to have attention drawn to their presence.
Lock your steering wheel with proper locking mechanism. Additional signs of theft protection devices discourage thieves from attempting to tamper with your vehicle.
When walking from your vehicle look around to observe people that appear suspicious or don't appear to have any reason to be there. For example, a person walking around in a shopping center parking lot looking around at others.