Using Subdivisions to warm up is key. Using a metronome in increments usually pushes you unnecessarily to play faster. This can be bad if there are any unnoticable glitches in your technique. VERY BAD. Because playing any instrument is about muscle memory. If your body is doing something wrong, it will most likely do the same thing but faster causing nothing but frustration. Play slow and pay attention to you technique during your warm up. It's more about warming up your brain to tell your hands what to do that anything else.