Who you are and what you do
The neat thing about the online world is that you are judged almost entirely by your actions, usually based on just your fingers.
If you do generous things, people think you are a generous person.
If you bully people, people assume you are a bully.
If you ask dumb questions, people figure you're dumb.
Answer questions well and people assume you're smart and generous.
... you get the idea.
This leads to a few interesting insights.
1. If people criticize you, they are actually criticizing your behavior, not you.
2. If you're not happy with the perception you generate, change the words you type and the messages you send.
3. When you hear from someone, consider the source. Trolls are almost always trolls through and through, which means that you have no obligation to listen, to respond or to placate. On the other hand, if you can find a germ of truth, can't hurt to consider it.
The biggest takeaway for me is this: online interactions are largely expected to be intentional. On purpose. Planned. People assume you did stuff for a reason.
Be clear, be generous, be kind. Can't hurt.