BEGINNER USER GUIDE 4.5:
Content warnings can be used in many situations. Most people require you put kind-of-unpleasant things under a CW, and you honestly should, because, well... it's the right thing to do!
If you also put an image on your status that's also kind of NSFW, you can have that be unseen until clicked as well by selecting the 'NSFW' option (or by hitting the eyeball button on the webclient).
CWs can be used for:
-potentially triggering stuff
-spoilers
-memes