[slavemason]

Take a look at a book called the Bass Grimoire by Carl Fischer (there are Grimoires for guitar, keyboard, and others). It's a little mind boggling at first so take it in small dosages. It's good about illustrating the difference in all the scales and modes. Some of I still don't understand. It's also good about showing all the positions you can play a scale on the neck. It's up to you to find where and what's comfortable.
As far as lessons go, I wouldn't take any longer than a month or two. They should teach you some good habits as far as right and left hand techniques. They'll also show you some exercises that will get your hands moving. Outside of that, it's up to you to practice.
Are you going to play with a pick or your fingers? I recommend the fingers, while some prefer the tone of a pick.
This post was much more interesting than some of you tummy rubs I've seen in the past. :/