I used to ask, “Would you refer us?”. The problem with that kind of question is that it leaves no room for shades of grey.
So I’m advising you to use a 1 -10 scale to identify someone’s degree of willingness to refer. This allows your client to tell you, “Well, I’d say 6”. That should then prompt you to ask the next question: “OK, what would I have to change . . . for you to say “10”?”
Going to your clients to learn, directly, WHY you are so remark-able . . . is a key to becoming more refer-able. Remember, this is about learning what it takes, on your part, to be worthy of being referred. And, If you’re not quite ‘there’ yet, this will tell you how to get there soon!