There are a ton of web sites and books you can buy.
Theory, part writing and composition are nothing but a set of rules. Take for instance the standard 12 bar blues, its a set cadence and progression, its a rule, if you dont play it correctly it isnt 12 bar blues.
The whole "cant end a progression on an augmented fifth" type stuff is shit tou know in your head, you know when something sounds like shit, or incomplete.
Over centuries ppl have figured this out and written it down. Thats all theory is.
Imo put to memory all basic scales then move to the more comolex stuff like minor 7 flat 5 (basic minor scale but flatten the fifth and seventh interval as well).
Learn to play all scales everywhere on the bass. Sysly even playing straight major all on the E string type stuff.
That will open your playing up big time and your chops will get immensly better also.
This book tought me way more than theory, comp and partwrting classes ever did.