Ending it well, and afterwards

Watch the time you asked for and end at it. Say what you took from the conversation — one specific thing, not a general thank you — and then ask the one question that reliably keeps things going: is there anybody else you think I should talk to?

Follow up briefly within a day or two, and tell them later what you did with the advice. Almost nobody does that last part, which is precisely why the people who do get remembered and asked back.