You start by getting a baseline. Watching how others interact, and respond to each other. You notice how different personalities have different priorities and how those clash and harmonize with other people's priorities. And from that, you can ask yourself the question how you as a person fit into that system. What's important to you? What do you prioritize? How do you feel about the situation they're debating? Without having to tell them about it, just ask yourself that. How come it differs from the other person's pov? Can you see where they're coming from? And why they are thinking differently about it than you? This will allow you to sharpen and outline your values more and pinpoint what value is important in which situation and when it can take a backseat. And it will give you security in the fact that those are in fact values you want to stand up for, and at the same time give you the insight you need in others to value what they are standing up for. Your emotional responses triggered by insecurity and self-doubt will lessen and you'll be more understanding to others, more accomodating without forgetting who you are and what your priorities are.
All of this takes a lot of time and effort. But it's worth it. Good luck to you