I’d say to spend lots of time with yourself in silence so that you can be comfortable by yourself and with your thoughts. Spending 100% of your time in the company of others can inhibit your ability to think critically by yourself (without outside input).
Also, thinking critically about your values and what you care about, and what type of life you want to lead will help you know yourself better and have more intention with how you do life.
Lastly, reaching out to mentors and reading about historical figures that you admire might help you learn how character can be moulded (because character doesn’t just appear! it grows and matures over time)