1. Start here:
https://community.upwork.com/t5/Academy/ct-p/Academy
2. Use the forums to ask specific questions about situations BEFORE you take action on something.
3. Don't do work for anyone without a contract in place, a funded milestone (if applicable), a verified payment, and ensure that the payment is only made through Upwork's platform.
4. Never give out contact info before a contract is in place, and don't engage in conversations with clients off the platform before you have a contract in place.
5. Any client who asks for payment for any reason in order to start work is a scammer and needs to be reported.
6. Use common sense, if it feels wrong, there's a good chance it is wrong.
