This is excellent advice. Just wanted to flag it for serious players.I personally would not say 4 scales, but the 4 arpeggios that will cover the majority of your bass playing are the Major, minor, Dominant and half-diminished (min7b5). You should know how to play these starting from any finger as well as how to play their inversions. In every key, all over the neck. Extra credit for knowing the notes of each chord!