Wired Magazine recently ran an article explaining the ways that Facebook tracks you. They also include advice on how to limit it, short of deleting your account.
To most of us, Facebook may appear to be free, but in reality we are exchanging the use of Facebook for some of our personal information.
Some quick tips (make sure to read the full article for more):
Check your ad preferences page on Facebook and make sure you're only sharing what you want to share with advertisers.
Go to this third-party website YourAdChoices. Wait for it to analyze the companies that are offering ads through your browser. When the list comes up, opt out of anything that you don't want.
If you use any of Facebook's apps on your phone, "Head to the Facebook permissions page—under Apps and notifications and Facebook in Android settings and under Facebook in iOS settings—to block Facebook's access to your phone's location, your contacts, your phone's microphone and camera, and more."
Ultimately, if you don't trust Facebook, but also don't want to delete your account, just use it less. Be a "social media lurker." Don't ever use your Facebook account as a login option for other apps.
Following some of these options will be a step towards protecting your online privacy.