Hi Denwand I work with celebrities all of the time and like much of the advice offered so far, be yourself and treat them like your other clients.
This has got nothing to do with looking at your own self esteem (the comment written about that was spiteful and very negative) it's about wishing to get the job done, as best as you can do and asking for advice is actually a positive, confident thing to do and shows how much you want to get everything right.
You will soon work which of these new clients are easy to work with and which demand more of your time.
Happy to chat directly if you need any further advice. This should be a new chapter which is fun and will hopefully open up more doors for your business.
Best of Luck