Crime in the Czech Republic is mostly non-violent in nature: purse snatchers and pickpockets operate mostly in tourist areas throughout the city. Be wary of groups of people shouting and shoving each other to get onto a tram or metro. This is usually a smokescreen for a pick pocketing operation. Do not speak to strangers who approach you on the street with offers for illegal money-changing. They can also be part of a pickpocket scam.
Residential break-ins are rare and seem to be deterred by adequate locks and lighting. Car thefts are prevalent throughout the city. Do not leave anything in view inside your car. You should view Prague as you would any large city and practice common sense security precautions.