Online dating scammers want your money. Never lend money to anyone online.
Are they asking you too many questions about your financial status? Nobody needs to know your finances until you have met in person many times and have established a relationship.
They will romance you and make promises for the future without ever meeting in person.
They may ask you to go into business with them.
They ask you to transfer money from your account to theirs because they are having problems with their bank account.
They may tell you they are in the millitary to gain your trust.
They want you to lend them air fare to come see you and will pay you back when they see you.
If they say they love you right away this is also a red flag. Love takes time to develop.
They will beg and plead with you for money so that you can both start your lives together.
If they are not willing to trade photos, or only send one photo, that is a red flag. Sending only one photo may be an indication that it is a phony photo. Ask to see more photos and compare them.
Anyone contacting you from overseas should be avoided. They may be Nigerian Scammers.
Stay safe and use common sense. You'll know when something doesn't appear right. Trust your senses.