How do you set Facebook so strangers can't send you a message?

[Seerah]

I have been bullied a lot of the times on Facebook. Strangers and those people who are not in the list of my friends keep sending me messages that are really annoying. Specially now that I am engaged I would really appreciate any kind of help in regard to blocking any kind of messages from those who are not in my friends list on Facebook.
Mind you facebook has changed. Most of the answers I got on Google for my question those were based on the old settings of Facebook. Now it has limited option.
Can anyone please help me.

If you could also advise how to block my pictures so that whoever is not on FB shouldnt see my profile picture at all...I have noticed some people have a profile picture up on their facebook but if you are not their friends you cannot see the picture at all..it is an empty friend unless you are his or her friend.

THANK YOU IN ADVANCE

[Yahoo mania]

Click on the LOCK shaped icon at the top right corner
Click on the dropdown arrow next to who can contact me
Choose Strict Filtering

[Lenny]

You can change your filter preferences right from your inbox.
https://www.facebook.com/help/116215745206219

Basic Filtering
If you select Basic Filtering, you'll see mostly messages from friends and people you may know (ex: friends of friends) in your inbox. Typically, messages from other people will go to your Other folder, and you won't receive a notification about them.
https://www.facebook.com/help/398578543552207

Strict Filtering
If you select Strict Filtering, you'll see mostly messages from friends in your inbox. Some messages from people you want to hear from may go to your Other folder.

Whichever filter you choose, you may sometimes get messages in your inbox from people you're not connected to. Some examples of when these messages may go to your inbox are:
A friend of a friend includes you in a message along with some of your mutual friends
A member of a group you're in messages you or includes you in a message
A friend who isn't on Facebook uses your contact info to send you a message from the Facebook Messenger app
Additionally, someone you're not connected to on Facebook may pay to ensure their message is routed to your inbox instead of your Other folder.