There is no better way to build a brand online than output. Let people know what you're thinking, doing, seeing, feeling, opining. Tweets, blog posts, instagram pictures, video blogs, guest articles, speaking at conferences, interviews, side projects, art, photography. The more you can produce the better. Each one is it's own little PSA that says "Hey, what's up. Remember me. I'm important."
Interestingly, we're at a point where quantity is more important than quality. We're living in an increasingly ephemeral culture with Snap Chats and endless real time feeds. The current output is judged moderately as there is always expected to be, either explicitly or implicitly, more to come. Another tweet, another post. (God forbid you have a few consecutive sub-par posts, that may be grounds for unfollowing).
The narcissistic edge of output is dulling as we all continue to struggle for scraps at the increasingly crowded online-relevance dinner table. VCs, entrepreneurs, journalists, celebrities, employees, thought leaders, industry professionals. If you're not out there, you're nowhere. And if you're nowhere online, then are you relevant offline?
All press is good press. Ahem. All google results on your name are good google results on your name.