Start with a self-brand audit.
Marketers do research such as small focus groups to gauge what’s special or problematic about the brand. You already have a lot of focus group information at your disposal too if you start observing.
What do people compliment you for? Criticize you for? What do you love to do? What do your clients or bosses say about you?
What are the themes in your yearly performance review? What are your strengths? What are the vulnerable areas? What new directions are your interests taking you?