Diversify your team.
Homogeneous teams create narrow designs; teams with diverse experiences create more inclusive designs. Be sure that members of your team don’t come from the same culture, age group, gender, or gender expression, and don’t all have similar experiences and educations. If your team is limited and you don’t have the ability to expand, actively seek out people with other perspectives to consult or act as project advisors, and give special consideration to their feedback.
Help your audiences inform your design.
Learn about your audiences: their motivations, needs, behaviors, challenges, pain points, and goals. Consider existing customers, prospective customers, your client’s customers, and past customers. It may be tempting to only pay attention to primary use cases, but get to know the less-common ones and design, review, and test with those in mind as well. Set up user interviews, split tests, and analytics so that your audience can inform your initial design decisions and later iterations.