Never leave the site
If a person, after a few messages asks you to leave the site be alert. Scammers like to take people away from the site and into a chat system like Skype, Hangouts or email. Stay in the site and you have more protection. Fakes will come up with some great reasons why you should chat elsewhere, they include:
Never send anyone money
This is a really simple rule, never do it! Whatever the reason they come up with, no normal person needs someone they have never met in real-life to send money.
If you have doubts
You can always test someone if you think they could be a fraud. Ask them to send a selfie with a pose of your choice, for example, 2 fingers touching their left ear. If they make an excuse, like my camera is broken on my phone, hit that report button!