Writing 'About Me' to introduce yourself on GitHub, Reddit, Twitter, and Instagram is hard, but a good rule of thumb to remember is:
Profiles are not about who you are, what you know and what you like (or dislike). Profile should be about:
How the community should know you,
What you bring to the community, and
Why the community should be interested in you
Ask these questions to yourself and then draft your profile.
PS. What is community? Every social media platform has its own community (and sub-communities) with their unique expectations, engagements and interactions. Identify communities that you are interested in and then tailor your interaction accordingly.