Can you say 'no'?
Not just no to creative people.
No to clients?
When they say they need an ad in two days, can you say, 'No, we need more time.'
When they say they have no money, can you say 'No. To do what you want to do, we need money.'
When they come back at the last minute with a complete change in mandatories and strictures, can you say, 'No. That's not acceptable.'
Mostly, can you say 'No. We are not a service. We make a product. A product that reflects your brand. If it looks cheap and slap-dash, you look cheap and slap-dash. No, I won't let that happen.'
It might be the most important word in your vocabulary.
Can you say it?