I been thinking about somethings lately. I recently decided to take a break from teaching for a while. A partial rant: students don't practice, or don't practice the right things!!!!
Ok this is what i have to say to those seeking to further their low-end ambitions:
Your tone - Like what FATCAT (meow) mentioned: the most basic thing - Sounding good. I really don't think playing an awesome scale with a god-awful sound will help in any way. While you (the beginning player) dunno how to navigate your fingerboard, wouldn't it be sensible to try sounding good plucking a couple of notes first?
Your knowledge vs your experience - Haiz this is one tough scale to balance. As a starting bass player, I confess that i dived straight into songs instead of 1) taking lessons, 2) buying a tuner, 3) asking around for feedback like some of the guys on Soft. I also went straight into a band after maybe weeks of playing (but i played drums and geetar retardedly for a year or so). Reason why i didn't get kicked out of bands was probably cos i had OK hearing. My point: If i learned all the stuff i did on the net + readings, but had nowhere to apply it full-force, I don't think it would have mattered that i bothered to learn. It still kinda sucks that I have Basic Theory but never went to take my TP.
Breaking boundaries (your own) - Ok. Don't fall asleep, we're getting there. Thing is, when one whores bands, or whore genres of music for the heck of it (as a bassplayer!). I think it'll help us more than guitarists. I won't say why, You'll just have to believe me heh. This isn't asking anyone to think out of the proverbial box, but to make your box BIGGER. The more missles you have, the better equipped one will be to learn new things. Can we smell improvisation now?
Ok, some may ask: Why can't i go to bass classes first, then seek out bands and then improve the crap out of my musical-self? My answer - You can. But some people might find it harder. One just has to find the best way about the journey. I can only say that the way i walked so far, has brought me lots of joy. So much that the 'pain' of learning theory has become negligible. In fact, I personally hunger for knowledge now more than ever, and I also want to play as much as i can with bands and musicians.
To just sum up on 'improvising': I believe strongly (duh) that theres no shortcuts, no tricks. Try anything funny and most people will see though you. Play 'dead scales which sound right but without a 'message' or conviction, and you'll be boring. When one knows what to say in a bassline, or even a bass solo. It'll just sound POWERFUL/COMPELLING, be it 2 different notes or all 12.