| Teacher, teacher, teacher. If you want to avoid lessons for some reason, you really should teach yourself at least the basics of theory and just get some technique tips to make sure you're playing properly. Basically, scales are good to learn, and it would be nice to get someone to coach you a bit on fingering and techniques such as slapping and tapping if you want to learn them. A teacher would be perfect in that sense. Also, as Jace said, they will inspire you to keep playing by challenging you with new songs and exercises. Ideally you should feel very comfortable with the bass, and develop a decent ear that lets your fingers play what your mind wants to be played. | 
