Are these referrals from your network or your past customers/clients?

From your network, you need to be very clear about the problem you solve, how you solve it, and the outcomes (results) you produce.  Then you need to get very clear about them (same info), so you can refer them.  

If you want customers/clients to refer you. That's a system you need to create to make it drop dead easy for them to do so.   You need to make sure you always talk about the problem you are solving for them, checking in to see if they feel you are solving it and reminding them that it's important because you always want to be doing work that would make people want to tell all their friends how smart they are for hiring you.  

As to what you can share.  A survey to collect this info ( by the way, I'm holding an event you might want to check out that talks about this part https://www.alignable.com/grou...

And use the information for a testimonial and an opportunity to send them some cut and paste copy they can use to share with people they would like to refer you to. ( don't leave it up to them to describe what you do)