After you have defined the user flow, it's time to get sketching. This is the stage when you want to generate as many ideas as possible and not worry about the quality. You can use pen and paper or digital tools — depending on what works better for you. However, avoid jumping into prototyping right away. It requires more effort and doesn't allow you to explore many approaches quickly.

When creating sketches, always keep users' goals in mind. For every design screen, ask yourself:

• What's the purpose of this page?
• How does this page help users achieve their goals?

Try to approach the problem from different angles. Create several versions of each screen, get feedback, and iterate upon them until you have a couple of working ideas.