Adding runs

[collicsws6z28]

I want to jazz up the basslines on some songs. Do I need to learn all the chords first? Are scales a big part as well? If so, could anyone give me a website with what's necessary to learn what I need to get some good runs down

[BillyRay]

You do need to know the chords and key of a song is you want to improvise over it or change the bassline around. Having knowledge of the fretboard and common substitutions (here lies most of the creativity, for rock music at least) is also important.

Having a good ear is paramount. Learning all the modes of the major and minor scale (and how they are constructed) will get you pretty far, but basic arpegios for the most common chords might be simpler/better for you depending on wich style of music you play. Having a good grasp of how chords are constructed (and knowing a little guitar) will get you a long way towards creaing interesting variations within a song.

Transcribing basslines (and other instruments part too) should help you with some basic fills and runs.