The holy grail is moving your ass back and forth when you play. Feel the funk in your whole body and then play to that, not the other way around. If you can't play a line without breaking the flow in your body, don't play it. Learn how to play something that works with your whole body, so it will work with the whole body of that sweet little lady out in the crowd who wants to shake something loose. You will know you are doing it right when a woman takes her clothes off at a gig. If you have yet to play a show where that happens, you need to keep practicing. If you have played a show where that has happened, then you know exactly what I'm talking about.
Here is an exercise to understand the approach.
Exercise #1
Right now, play some air bass. After a few seconds, imagine what you would actually be playing if you were holding a bass in your hands. It might be something like "bepop shoo boppa doo twiddly twiddly scoobadoobadooba."
Exercise #2
Stand up and violently thrust your pelvis back and forth. After a few thrusts, imagine what you would be playing if you had a bass in your hands. If you thrusted correctly, chances are you would imagine playing something like "BAM! BAM! BAM! BAM!"
That's the funk. It will fill up the dancefloor every time.