Account privacy, strangers accessing my profile, keeping account visible to personal frtiends only.

How do I make sure only my personal friends can access my account and personal details, and all else about me?  I keep getting messages of sexual content that i did not subscribe for from strangers, and women at that! I'm a woman and i'm definitely NOT INTERESTED. Is it enough to delete said contact or do i need to do more to avoid future unwanted messages of any type?