another method that i do, which isnt always possible because of a limited selection, is to study different bassists but in relation to a particular song. See how the bass player approaches different parts of the song and does certain things. Then get the same song but done by different groups and pay attention to what the bassist for that group does. Once thats done then a compare and contrast can be done, particularly noticing whether different note choices are simply alternatives, or do they significantly affect the feel of the song.
right now i want to work on my slapping. to me it sounds musically stale and repetitive. so im going to start studying marcus miller. really listening to his music, trying to identify his patterns and more importantly the reasons behind his note choices.
studying basically is trying to understand the "why" behind their playing, more than the "what". and very profound musicians have a strong "why" because they arent just randomly hitting a flurry of notes. They selectively, albeit subconsciously, pick notes to serve a particular purpose. Once you understand this you'll be able to understand how you should play for a particular song (whether it may be a borrowed line or an original creative one), rather than just being able to hammer out someone else's riffs that may totally be out of context and have an unintended response.