So, first rule is don't trust anyone. Check the following tips.

1. Even if you decide to continue to write to the person, STOP at the moment she talks about money. You can't put a price on love.

2. Scammers don't have time to sit down and write all these emails to a lot of people.
They write a number of emails in sequence and then make some kind of automatic script to send them.

3. They send 1 or 2 emails from one account, then close the account so they can't be traced, send a couple more from a different account and so on.
Someone who's really interested in you, writes you from the same email address so you can just hit "Reply" and keep a chain conversation.
ALWAYS use "Reply" on your email interface if you can't see the sender's address.
If they close an email account you'll get a "Delivery fail" from your email provider so it's easy to spot.
If your email program has a "Receipt" option, enable it. Scammers don't bother to read your emails since it's all automatic. So if you get another email from the scammer without getting the "Read receipt" from the previous email you sent, you'll know you're being scammed already.

4. Scammers write long and descriptive emails after the first time. They always send photos to lure you even if you didn't ask for it.

5. Because of the automatic process of the scammers chain of mails, TRY to make as much questions as you can. Write them in BOLD. As soon as you notice you don't get your questions answered in the following email, you're being scammed.

6. Scammers never tell you where they found your email. They say they don't remember.
Also, they never use your name. They say "Hello Dear" or "Bye Honey" (This is perfectly normal if you write to someone long enough and you start to use pet names or tender words but NOT with someone you just met).

7. Scammers send very provocative or even naked photos on the first few emails. That is not proper behavior of a serious person.

Please feel free to add your comments and advices.