Alumni networking - What to ask and how can I ask for a referral?

Hey guys,

I have two calls next week with two different alumni (one working as an associate at a BB in London and another as an associate in PE in NY)

Except asking about his background, how he get there what keeps it in the industry, I would like to know whether you have some advices, to make a good impression and possibly to ask for a referral at the end of the call. In my email, I say that I want to know about him, his background and to help me for my applications (CV, CL and interview questions).

Thanks !!