1. If the offer is too good to be true, then it is not true. Some scammers offer thousands of dollars in exchange for doing a very easy work. If the offer is true, then thousands would have tried doing it.
2. If you have to pay in order to start your work, then it is a scam. Remember, it is the employer who should pay you.
3. If the employer does not tell you how you can get paid, then that job offer has a problem. You should know how your prospective employer should pay you.
The bottom line of the whole matter is that legitimate work-from-home opportunities do not come easy. Determined beforehand which type of work interests you. Search the client on your own. Remember the red flags and stay away from scams. It may be difficult, but it is always worth it.