When I start a design project, the process that I follow is described by the Nielsen Norman Group   in their Design Thinking 101   article.

It is a user-centered process that starts with user data, creates design artifacts that address real and not imaginary user needs, and then tests those artifacts with real users.

This process consists of 3 flows:

understand explore materialize

Further defined by 6 phases:

One important takeaway from this process is that it encourages flexibility and iteration through the phases, repeating as needed. It is not a rigid set of steps to follow.