All projects are different, so I mix and match design processes and techniques based on complexity, creative direction, budget, and time constraints.
Identify the problem and desired outcomes. Research the market, research competitors, collect data, talk to people—learn more about the problem and its potential solutions.
I'll usually start with a sketch. Anything goes. Sometimes I'll sketch on paper, or on a device. Sometimes the sketch is just a doodle.
If I'm starting with a more solid design concept, I'll go into wireframes so I can start exploring layouts. Wireframes will vary in detail.
Defining more of the overall characteristics of the aesthetics. What is the design language and what is it supposed to communicate?
These can be fully functional prototypes or display-only prototypes. Like wireframes, they can vary in fidelity. For physical products, the sooner you can get a prototype the better.
Feedback / Refine
Collect feedback from key people and make decisions based on that feedback. In practice, the collecting, interpreting, and prioritizing of feedback is a daily event that happens throughout the life of a project.
Launch / Publish
The project is live! So, what next? Repeat the step above.