With learning any instrument, often the hardest part to gaining any fluency is being able to bend your fingers to stretch out even to the furthest notes and do so with finesse. So if you wish to become a famous bass player in a rock band, one of the best things you can do to help with finger fluency is simply practicing a few drills.
Try out the drill presented in this video. You'll learn how to play the bass line to the popular song "Parklife" by Blur. This tutorial is good for bass beginners as the bass line to the song is relatively easy.