Know key terms in camera specifications. For example, 35mm is the film stock that most motion pictures are shot on and "FPS" stand for "Frames Per Second," with 24 being the standard speed. Knowing what key terms mean will provide you with an understanding of how a camera works and what it's capable of.
Understand the difference between digital and film. Even though movies are shot on both formats, they are very different and can impact a movie in various ways. They each capture light and record images differently, which affects the look of the movie. Furthermore, film stock has a texture that also affects the look of a movie. There is also a significant price difference when making a digital movie versus a film movie, with film movies being far more expensive.
Understand what camera suits your purpose. If you want to shoot a mostly handheld movie, it would be best to use a camera that is easy to hold for long periods. If you want to shoot in predominantly low light settings, you should use a camera, lenses and film stock best suited for these conditions.
Know that price doesn't always relate to quality. "Paranormal Activity" was shot on a home video camera and "28 Days Later" was shot on a "prosumer" camera, proving that low-end cameras can still work on a successful movie. With this in mind, don't assume that the more expensive cameras are automatically better. Choose a camera that fits into your price range and suits your desired purpose.