Hi boilingTheDead 
Of course you need scales!
Imagine a bass with fur or feathers.
Back on topic:
Listening is a good approach! (the best "start" if you ask me)
Learn how to recognize intervals (sing them, than play them)
Train your ears to hear the difference between major and minor chords.
Most important thing: Have fun doing it!
Scales: Scales are great to get your technic right (right hand as well as left hand!)
Practice major, minor and pentatonics in all positions. It will help you to play properly and to develop stamina.
Leave some notes out (every second, every third or play only every third…)
Again! Sing with it because...
Improvising is playing the melody or line that you have in your head.
Leave the noodling to the guitar players.
may the bass be with you
Wise(b)ass
btw: When your guitarist is a Jimmy Page fan, learn the mixolydian scale.
Are scales what I need?
Of course you need scales!
Imagine a bass with fur or feathers.
Back on topic:
I want to be able to improvise immediately above any chord.
I can follow pretty much everything by ear playing the route note and from time to time playing an octive or the fifth
How to start?
Listening is a good approach! (the best "start" if you ask me)
Learn how to recognize intervals (sing them, than play them)
Train your ears to hear the difference between major and minor chords.
Most important thing: Have fun doing it!
Scales: Scales are great to get your technic right (right hand as well as left hand!)
Practice major, minor and pentatonics in all positions. It will help you to play properly and to develop stamina.
Leave some notes out (every second, every third or play only every third…)
Again! Sing with it because...
improvise immediately
Improvising is playing the melody or line that you have in your head.
Leave the noodling to the guitar players.
may the bass be with you
Wise(b)ass
btw: When your guitarist is a Jimmy Page fan, learn the mixolydian scale.