Recently some Twitter users have received direct messages that have fake Facebook links. Clicking the fake link could cause you to download malware. Another recent scam involved a fake Facebook notification that indicated the message recipient is in a newly uploaded picture. The message says that the picture is in the attachment. The attachment doesn't contain a picture but malware. Other recent scams include various phishing scams and "like-baiting" (promising free gifts in exchange for clicking the like button).
Use caution when granting access to your social media profiles.
Review your privacy settings regularly on each network.
Check out the social media specific settings in your security software.
Don't click on links in messages that seem out of character from the sender.
Be stingy with your personal information. Provide it only where necessary and only after you have checked out what it will be used for.