Chord tones or scales. Both. Some of us are working through Ed Friedland's Building Walking Bass Lines and it seems like Ed is taking us to a combination of both, i.e. using chord tones but the chord tone riff will insert approach notes from the scale. Hard to describe here with out you seeing the book.
I'm so stuck in my 4/4 four beats to the bar World I have problems moving from chord tones to scale tones in my playing. BIAB would be a good place to practice this.
As far as progressions go, there will be hundreds of choices you can plug in. I'd start with the basic I IV V I and ii V I
then read what
www.musictheory.net has to say. Go to Lessons then Common Chord Progressions and throw in some of the things they talk about. Sub ii for IV, use viidim instead of the V, things like that. Work on some turn-a-rounds like viidim, iii, vi, ii, V7, I.
Let us know how it goes.
Good luck.
