Study different styles of bass playing.
There's so much to learn; Funk rock uses slapping and popping techniques, metal uses the "driving" and "galloping" bass lines, there is Flamenco style finger picking, etc.
Also, practice both finger picking, and using a regular pick; I suggest Dunlop brand picks, because they're easy to handle, and generally aren't too fragile. I can't use a pick with too much bend.
Most important of all, have fun with it. When it becomes a chore, it becomes pointless.
Good luck.
