I play double bass too, and love this instrument; what helped me a lot is practice to get proper Tone and intonation and most important of all; the time!
Just take a basical blues, put that metronome on beat 2 & 4 at 60 or 80 bpm start playin half note on beat 1 & 3 with only tonic and fifth of the chord. Work this in different keys (all?) When you're feeling good, keep it and enjoy it!
Then you can 10 or 20 bpm, and or change song, rythm changes or just another ... song...