I'm totally self taught and I think I have done ok so far. I dunno if anyone else will agree with me here, but I feel that I have developed a technique, perhaps even style, that I like to think is individual...like a second voice I guess. When you engross yourself in music theory I think it's too easy to over develop your technical ability as oposed to your style. In the first 10yrs of playing the bass I never had a lesson by a professional musician, picked up a book or even watched a video. I learn't by listening and emulating my favorite bass players and mixing everything I have picked up into my own expression. I'm not saying you don't need to study...far from it. Music theory is very important to become a professional musician. I only started to learn music theory about 5yrs ago when people started to ask me to teach them. I didn't know what what to teach them as I didn't it understand myself! I didn't understand what I could already play and why I played it. My good friend Jon Caulfield gave me a few theory lessons to help me glue it all together. Basic scales and modes to start off with and applying it to different styles of genres. It didn't sink in for a while until I was asked to perform on my first jazz recording. It was all very free form and I was incredibly nervous as I was stood in a room full of very experienced jazz musicians. Up until that point I used the theory I had learnt for warm up excercises, but after a couple of hours playing with those guys everything started to fall in into place! The music that I listened to started to make more sense to me. It only made me wish that I learnt it all that theory years ago when I was a kid, but I am glad I didn't in a sense because I think I would be more mechanical in my style and techniques. I now teach a couple of very talented young musicians, but I only teach them basic theory. I encourage them to listen to as many genres of music, styles and techniques as they can so that they can find their own voice.
Whether you self teach or go to a tutor once or twice a week you have to practice, practice, practice. You must nail the basics and keep those fingers supple and dexterous. Most of all, you must have patience. We all can't play like Stanley Clarke in just a few days! Don't be afraid to ask! If you are having difficulty ask a well tuned musician to help you through any difficulties you may have. It took my 10yrs to do that because my pride got in the way, but take it from me...if you are not humble, pride will grind you to a halt. Being a musician is all about self improving and leaving yourself open.
Be inspired, be blessed!!!