Lately I am obsessed with learning to play jazz on a double bass (also called string bass, stand-up bass or acoustic bass). I give not a scatological expression for anything else. I get on these kicks, where I want to learn as much as I can as quickly as I can, about a subject that interests me. So I listen to jazz music, paying particular attention to the bass, I read articles on how to play jazz bass, I play exercises, I read musical scores, and I play along to backing tracks. Lately I have even used a free musical notation program to write my own bass lines from the chord sequence of a song, e.g. "Blue Monk."
Today I finally understand what a 1-6-2-5 chord progression is. There are many other chord progressions with similarly strange numeric descriptions. The 1-6-2-5 is used in basic blues progressions known as "rhythm changes," in such songs as "I Got Rhythm."
In other words, when it comes to double bass, I am attacking on all fronts simultaneously.
Ultimately, after digesting a ton of music theory, you have to actually sound good. So lately I have emphasized playing to backing tracks or the recordings of actual songs. I don't want to just ad lib, I want to play the chord sequences in clever but accurate ways. Sounding great on bass is the one overriding goal. All the rest of it, i.e. the theory, just supports that goal.
I am in my second semester of Beginning Big Band class. The band leader is a gigging jazz trombonist who really knows jazz and swing, and he is leaning on me to improve (he seems to like me, though). He is always telling the brass section to "Listen to the bass! Listen to the bass!" The bass lays down the rhythm and chord changes that keeps the rest of the band on track. If I screw up, the whole band can get lost, especially the soloists. That's a lot of pressure on me not to screw up (i.e. losing my place in the song's bar sequence).
I have learned a lot in the past few months, but there is so much more to learn.