Good bass playing, like anything really, is simple once you break it down. Play some notes from a scale in interesting patterns using good rhythm and technique and you have a bass line!
When you start to think like this, you come across all sorts of elements that you can include in your practice routine.
This video lesson is taken from my book Complete Fingerstyle Bass Technique. It comes with a free backing track and TAB/notation which you can find by scrolling down.
The example is in the key of C Major and the C Major Pentatonic scale is included in the PDF. I have a load of lessons that go into theory, scales, and improvisation. If you're unsure where to start looking for lessons, I recommend starting here.
Bass Backing Track & TAB/Notation
I also have a few more sample lessons from the book: