Barack Obama has over 31 million fans on Facebook, so perhaps his advice about using the site comes with expertise.

He offered his two cents in response to a question from the reader of the magazine US Weekly, according to excerpts posted online.

A 16 year-old reader from Detroit asked Obama for advice the president would give someone who aspires to reach the Oval Office himself.

"Be careful what you post on Facebook!" Obama said, according to the magazine.

"And most of all, take your education seriously," he added. "I'm only where I am today because I had great teachers and access to great education, and because I worked hard in school."

Obama's social media presence -- which includes his Facebook, Twitter, and representation on other social media sites -- is largely managed by his campaign, although his campaign has said he will occasionally make posts himself, which he signs with his initials.