It has less to do with the private personal information you have in areas of the site and more to do with information you post publicly in the forum or chat.

I'll use an example of someone on another website. He revealed his first name, his career, and the state in which he lived. Using only this information, I was able to find his full name, his daughter's full name, his address, phone number, and a legal dispute between him and one of his patients. And that was just searching on google.

My advice... Use pseudonyms for people you mention in forums and in chat. Be somewhat vague about your career (e.g., if you're a professor of economics, leave out the bit that you're the Department Head of Whatever University). Refrain from revealing the city in which you live (unless it's as populated as New York). You may even want to refrain from revealing the state in which you live. Do not post any news clips from the city in which you live or mention that such-and-such event happened near you. Do not post any information that can easily be found in news clips (birthdays, military/college graduation, tragedies, obituaries, fundraisers, and so on). It's very easy to use a date, a first name, and search term to find the original news clips which hold even more personal information. Lastly, don't post pictures that contain revealing information (pictures of buildings with the address number on the building, pictures of cars that show the license plate, etc.)