Never give personal background information as this can be used for identity theft.
Ask to meet. If you cannot meet a potential partner, they probably do not exist.
Do not supply additional images of yourself or your family as these can be used by a scammer to scam someone else.
Never provide specific information like addresses or home phone numbers.
During the first communication, they want to know what you do to earn your living. It tells them if you are a good financial prospect.
Never tell a potential date any detailed financial information.
If you suspect you are being scammed, stop contact immediately and report the scammer to the authorities. In Australia there is a website called www.scamwatch.gov.au. There are similar sites in other countries.
If you are emailing, Google has a feature that shows you which people are in their circle. It might be a different user but the same group of people.