how do you change someone's mind?
Probably a good start is not to go into the interaction with the goal, "I'm going to get them to believe what I believe." It sets up a barrier and puts both parties' beliefs under lockdown. No matter how attached you are to what you believe, for a fruitful exchange to take place it's best to enter it with an open mind, and that means recognizing that your beliefs are subject to doubt just like theirs. Growth can take place when you form a true empathetic connection and meet as equals, and that can only happen if you're sincerely open, listening to and feeling the person you're talking to, and you maintain that even if they are defensive or even offensive towards you. A good start is to feel where it is that you can warm to them. If they're racist, is that because they're afraid of something, and can you feel and relate to their fear? I know this is vague, but the agenda can't start with specific actions on specific beliefs.
And how do we add beliefs? We're born with certain tendencies, during our upbringing we imitate and are trained, learn what rewards and what brings pain, and form social bonds. Our likes and dislikes take shape and we start to be driven by these, and we form habits. Social bonds and habits soon turn into our assumed identities, and this whole submerged iceberg of arational formation lurks beneath the visible tip of our rational thinking. Mostly we form beliefs to suit what's already there and avoid discomfort, though we may think we're being awfully rational and objective. Being aware of this can help when you encounter someone whose iceberg happened to grow into a different shape from your own.