People who initially find you on the Internet have only that content by which to judge you. Humans generally take initial impressions to be the reality about another person. So, if the information they see about you is slick, well-informed and professional, researchers are more likely to have a positive opinion of you.
You can take steps to help shape that impression. Use a professional e-mail address (not a free account from Gmail, Yahoo, or other providers). Carefully re-read e-mails and blog posts for grammar and spelling before you upload them.
Realize that the more time and effort you put into online content -- in other words, the more you value that content -- the more likely that other people will value it, too. On the other hand, people immediately spot fluff or inconsequential content and move on.
Worse yet, they will fixate on salacious or dramatic content that's embarrassing. You want to avoid that kind of content when possible. Instead, present a perception of your professional demeanor whenever possible.