My personal experience as a student, teacher, and performer is this:
Practicing includes getting your chops smoothed out (scales, chords, and rhythm) a metronome helps.
after a warm-up with that, try learning the different parts CORRECTLY at a slower speed. After you have learned the segments, join them together at that slower speed making sure to play them through COMFORTABLY. As your comfort level increases, try increasing your speed. If you make mistakes, stop, take note of where they are, and back up on the speed until you are playing it correctly.
Playing is a part of practicing. That's my philosophy. Think about it.. the more that you do something, the more experienced you get. Every time you play with your band, you get better. And one more word of advice: Whenever you pick up your instrument, warm up your wrists and hands.. either massage them, or do some stretches. If you don't, your hands will cramp, and that sucks.