Stay on site
... and keep all communications on the dating website you are using. Be wary of anybody asking you to talk with them outside of the dating website after only a short period of time getting to know them.
Don't be convinced by profile pictures
Romance fraudsters tend to use photographs taken from the internet. You can check photos using a reverse image search on websites like www.tineye.com or reverse.photos to see if they have appeared anywhere else using different names, or impersonating someone else.
Do your own research on the person
Are they members of any social networking sites? Can you confirm what they are telling you about themselves, where they work or where they live?
Are you sending them money?
Never send money to someone you have not met in person or do not have a way of getting the money back if something falls through. Be extremely wary of giving money to someone you have recently met, particularly if you have only recently started a relationship with them.
Are you receiving money?
Be very wary of anyone asking you to receive money on their behalf and transferring it on to someone else. They may be using you to launder money.