This topic seems more like how to project manage a Tableau related project and that will have a number of things to consider depending on the customer requirements. A high level list is to understand the data sources and have access to them. Understand the customer requirements from an Objective view - what are they trying to accomplish? Too often we seen people come to the forums with some strict requirement to have x thing a specific way while totally ignoring the customer need for information in pursuit of a specific method.
So in short - make sure you have access to the data you need and you clearly understand the business need/requirements of the customer. That would be my recommendation.
I hope that helps.