I used to think scales were the most important things to work on as far as music vocabulary was concerned, but the more I played and studied the more I realized that triads and arpeggios are the most important part of music vocabulary to really have down. The problem is that you really need to know what a scale is and why a scale is what it is to really understand theory behind arpeggios and triads all the while knowing that all of these things are just a way of organizing, indexing, and cataloging your notes. As I have stated before the triads are the harmonic material all the bass lines you have played and will ever play. The way I like to work on composing a bass line for a particular groove or tune is to find what I call the harmonic and rhythmic core and build from there. The following video gets into the first important steps of this process. If you are interested in improving your playing I hope will consider Live Online Skype bass lessons with me.
I can help you get better. – Russ Rodgers