I want to start building relationships with influencers/bloggers in my industry; when I interact by commenting on their blog site, on twitter, facebook, etc. should I be using my personal account or should I be using my website brand account?
Personally, I would use your personal account when it comes to commenting on their posts and interacting on social sites. They'll be able to tell that you're associated with a specific brand/company, and acknowledge it. While everyone enjoys having brands interact with them, and comments on how smart and on top of things they are, the reality is that individuals want to connect with other individuals, and will like the brand by association with that individual.