what is the best practice between an Agency and a client in order to maintain a long fruitful relationship

I always told my agencies to be more Proactive. I wanted to have business partners not Agency-Client relationship.

Agency representatives/account directors need understand and FIGURE OUT my need. so instead of delivering what I WANT, they need to give me what I NEED. so by being proactive as an agency, they understand my business question to be answered, then they offer a specific research/product to answer my question. instead of me telling them how the research/product should look like!

I think one of the best practices would be to sign off creative briefs. clear requirements avoid unnecessary problems and thus maintaining a long fruitful relationship.