New job in advertising. Any tips or knowledge you might want to share?

I'm 23 and I just got hired in a well known advertising agency, but my degree, and what I'm most capable of, is journalism. My duties in this agency are in social media, and I need to manage the Facebook Fan Pages of a few beauty brands. Also, do beauty advertorials.

Have any of you had this kind of job or duties before? Share your experiences and knowledge with me, Reddit!