I would like to use my old boss has a reference. However I'm not sure if he will give me positive review (I think I did decent/good work at the job but we also had a few conflicts). Should I ask him if he will give me positive reference before using him? What is the etiquette? I did ask him if I can use him and he said yes.
I don't want to use him if he will give me a lukewarm reference.