Taking the first step is always difficult . I too have experienced this scenario numerous time when I took up a project and was overwhelmed with the information presented. The mind loops aroud is this the correct way or is that the correct one. With time and applying different strategies I am sharing the first step that has worked for me very effeciently.
The first step I take is separating facts and assumptions from the clutter of information.
Our communication is usually a set of facts and assumptions and the it is also true for most of the projects that we take up in life. So when we receive any information in the first thing we should always try to do is separate the facts and assumptions. This also serves as a very good starting point because it motivates you too ask a lot of questions to accomplish this.
For example, considered you have been asked by your manager to increase the sales by 30% this quarter. The first question in this discussion could be : Why 30? Why not 20 or 100? What we are trying to figure out is , is the value 30% is an assumption or based on a facts.
If it is based on assumptions, the first step will be to validate all the exemptions if it is based on facts the first step will be to study the validations and the data that came as a part of the study.
This conversation also has a hidden benefit, it serves as an icebreaker with a new team.
Try following this mantra and see if it works out for you and trust me after this the second step will be much much easier.