I like to correct grammar, punctuation, spelling and capitalization errors. I am not an expert, although technical communications is what my degree is based on. I just simply enjoy it. Occasionally I'll be guilty of editing content, but only to reduce redundancy and to clarify confusing sentences, paragraphs, or articles.
I like Gregg's Reference Manual to refer to, as well as the online version of the Oxford dictionary.
Other than that, not much else to tell.