By and large, Birmingham is a relatively safe place to visit - certainly no worse than any other large UK city!  As usual, there are a few simple precautions to take when visiting:

• Take care when crossing the main roads, and use a pelican crossing where possible.  There are a number of dual carriageways running around the city centre, and although the speed limit is 30 or 40mph, speeding is quite commonplace.
• Taxis - always use black cabs, or else book a private hire cab by phone first.  If you flag down a private hire car on the street, you will not be insured in the event of an accident.  There are also a small number of drivers that pose as licenced taxis of an evening - don't get in a car unless you are sure it is a licenced cab - it will have a yellow plate on the back with details of the licence.
• As in any big city, there is a risk of pickpockets, so keep your bags zipped and your valuables secure.
• The main areas for nightlife (Broad St, Brindley Place, Chinese Quarter, Hurst St etc) are generally pretty safe, well-lit and adequately policed.  However, it's best not to stray away from the busy areas late at night, especially if you are alone.