Welcome to the bottom end. Most everything you learned on the acoustic 6 string will transfer over. Just remember we do not strum, we play the notes of the active chord one note at a time to the beat of the song. It's a lot like playing arpeggios. Bass Guitar for Dummies is an excellent book to get you started. It will go into detail on how to hold your bass, how to get sound from it, how to tune it, etc. all those fundamental things that you must learn first. I always work best when I can see the big picture of what is expected. Here is an overview of what you will be doing. For example:
When the vocalist, or solo instrument, is singing or playing we play accompaniment - using the notes of the active chord. First question what notes? The root, 3, 5 and 7. I never go beyond the 8 octave and leave the second octave 9, 11 and 13 notes to the solo instruments. Roots at first to the beat of the song; R-R-R-R. When you feel comfortable with that move on to something new. Something like R-5, R on 1st beat and 5 on the 3rd beat, then R-5-R-5 fills out a 4/4 measure nicely. Then the 8 is always nice and generic R-5-8-5. After that get the correct 3 and 7 into the bass line, i.e. R-3-5-b7 if playing under a dominant seven chord or R-b3-5-b7 if playing under a m7 chord. This is going to be new and will take some time. Remember how long it took you to get the finger pattern down for the basic 21 chords you strummed. Same thing here; get your major, minor, dominant seven and diminished chord tone notes (scale degrees) into muscle memory. See a Cmaj7 chord coming up in the music and your fingers know where to find a C note on your fretboard and then where it's 3rd and 5th and 7th are located.
http://www.smithfowler.org/music/Chord_Formulas.htm Yes we think in A, B, C and 1, 2, 3.
You will want to run your scales so your fingers know where the notes are located on the fretboard and your ears start recognizing the good notes from the bad notes. I know of no instrument that does not start you out running the Major and natural minor scale. It's a right of passage thing.
Have fun it is a journey. I recommend you start on page 1 of Dummies or sit knee to knee with a live instructor.
