One small thing that works for me is... I start out playing basic changes/chords/bass lines, then I seem to get "bored" after a while. That's when I just let my mind wonder while playing and good things usually come out. Kind of like brain storming ideas. Then you just keep the ones you like and build on that. Before you know it, you are playing original lines.
+1. That's a easier way of saying what I did.