Existing customer is better, they have more knowledge about your
coy so easier to handle.
Just like talking to a normal friend, joke a bit then serious
abit.
You can stay calm and have some confident, you won't lose that
customer one... Since they choose to come back to your coy, it
means they are partially relying and trusting your coy, they might
need you more than you need them. However don't be over complacent
or cocky 
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wait.. this is crap box, must crap abit
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You pay your boss $20 cab fare, tell later you need foruming, can't
meet the cust. Tell him to update you on any news after the
meeting... 
