Well take the tune I posted, for instance. Looking back I remember that I was taking tunes that I play and recording them slower than normal to try to just focus on the "shuffle" in the bow. To start out the day you could just practice the shuffle of the bow, with a metronome, on any string or note that you like. Keep the bow really light and your wrist very relaxed. Then when you get comfortable, pick a tune and just work a small phrase of the tune. Try it in different places on the bass and just be happy with what you get, don't be too judgmental. Look for that part of the bow that feels nice and springy. If you keep at it, you'll start to get parts of tunes, and then whole tunes together. Like any kind of music you will start to see patterns in one tune that open up new tunes. Then it just sort of goes from there. Later you'll find that it can be harder to play them slow than fast.