Two of the most convenient ways of getting around Beijing are the metro and the bus network- both fairly fast, efficient and reliable. Bus rides, however, can tend to get tedious (Beijing’s roads are all arrow-straight and pretty monotonous at times), besides being often crowded, smelly and potentially hazardous due to pickpockets. The metro is much cleaner, but also gets crowded at times. If you’re willing to spend a little more, taxis are available, and are a good option for a relaxed and hassle-free ride. There are cycle rickshaws too, but, unless you’re good at bargaining, you might just get ripped off.
For getting around town on your own, there are two options: renting a car and renting a bicycle. The former can be pretty tedious and long-drawn, though, as you are required to present a work card, a residence card and other documents- so (unless you’re a long-staying tourist or a resident) it’s not really an option. It’s much easier to hire a bike- a normal one or a mountain bike- and once you get used to the vagaries of Beijing traffic, you shouldn’t have any problems getting around.