What to do when interviewing or meeting someone Successful

First email/call anyone you're meeting in advance and ask them their expectations for the interview. This is also an excuse to get to know them to see if your personalities click. Ask them what they'd like you to ask even topic points and if they'd like to have any special accommodations in the interview or any type of questions/topics they like getting asked. (Make sure to keep this email or call short no longer than 30 seconds of reading.)

Then figure out how to blow their expectations out of the water. Ask great questions that show you actually read their stuff (read and everything about them). One of my favorite interviewers is Jake Hamilton check him out (he happens to interview movie stars and directors doing a great job):

Perhaps reach out to him and ask for tips?  Perfect excuse to do so. In fact reach out to everyone who is successful and use any opportunity as an excuse to expand. Later perhaps you can interview them and other people in the field you like as well. This is a simple way to leverage success and build momentum.

Think of 10 ideas for each of the people you're interviewing/meeting to make more money/succeed. You should always be coming up with ideas to create more value for everyone on whatever they need help with.  James Altucher talks about this check him out: http://www.jamesaltucher.com/2012/10/how-to-become-an-idea-machine/

One idea example for a movie director would be: create social media accounts and do QA sessions once a month with fans to build up movie hype and enhance personal branding. You can also suggest they interact with anyone on twitter or other sites who are talking about similar movies. Or maybe suggest to do it for them if they are too busy. The importance is the value of the idea, people will naturally want to give back if you give first.

Everyone always wants something, so by helping them you help yourself. Another great leverage point is to use the ideas you give people for yourself! Perhaps you should make a social media account? Or do QA sessions?, etc whatever those ideas could be, some will apply and they'll be gold.
If the person asks for help on anything say yes. Figure out a way to get it done! One way is by asking other people for advice on whatever the task is.  :-)

Out of one opportunity create more and then out of those create more. Leverage is the name of the game, figure out how to get it out of everything. I for instance will use this content after I heavily edit it to make it sound more like a blogpost and even less like a talk directed for you. (this post was originally an answer to a person I know).

One thing you can tell everyone is: “You’re obviously an expert in this situation not me, how do you suggest I make the most of it?”

Then after they give you an answer, ask them again later to see if they expound more information. People will help you if you figure out how to help them first. The person who has contributed more always has more leverage.

After the interview or meeting write a thank you email. In that email ask them a question and tell them you'll follow up in a month. (again make sure it’s less than a 30 second read in the email). The question you should ask them should be short, but be very specific so they can actually give you good advice.  Make sure you’re grateful as well and they know it. You have now started a monthly cycle with this person you can email (if you played it right).

You might want to get them to be a mentor, if you do then I also suggest you read this post by Ryan Holiday on how to find one.
http://www.ryanholiday.net/finding-a-mentor/

None of the advice I just gave you is guaranteed to work. Hell, everyone wants a guarantee in life, but they don't exist. The only way to make something happen is to control what you can.
Good luck with your next meeting/interview.

Bonus tip:

You might ask, when is the best time to contact successful people to get this started?
Contacting successful people and politely interrupting them is virtually the same thing in our world. As long as people don't give you a direct no, such as: "Very sorry, but can't do this thank you" or "Sorry man heads down right now super busy", keep contacting them. You want to show them that you aren't the type of person to quit easily. 

I for instance just asked Grant Cardone a great entrepreneur from twitter the question: "What is your tip on networking with successful people" about 7 times before I got a tweet in reply. His answer was: "just tell them the straight up of what you want and then persist bit 3-5 times". I was prepared to ask him the same question 20 times daily as long as he didn't say: "leave me alone" then  I keep at it. The trick to keeping at it is to be fresh, don't just say the same message or even use the same platform for contact.

Kind of like a girl (or guy) that never directly tells you they don't want to go out on a date with you, if you persist enough you'll win. Obviously you don't want to stalk anyone so do it the right way. I tried different tactics/channels to get Grant to reply, I ended up having to tweet his wife and she got him to tweet back to me.  There's never going to be a perfect time for anything, the only time you have is now, that's when you strike, this game is about timing and there's no time like the present. :-)