You've taken an important step toward understanding how you perceive others and how others might perceive you. We all have preconceived notions and prejudices that we’re frequently not even aware of. These assumptions then affect how others treat us and how we treat them. Because we all make these assumptions, it is important to gather information, suspend judgment, and listen respectfully.
When assumptions turn into firmly held but inaccurate beliefs or stereotypes they become a problem.