How will I handle international payments?
International bank transfers and currency conversions incur fees. PayPal is one option, but there are fees for you to withdraw your money to your bank account. Consider using a service such as Transferwise.
Do I invoice in my currency, or the client's?
"I want to always know what I'll be paid, and not be vulnerable to currency fluctuations. I will always invoice in my own currency."
"I want to be flexible, and make it easy for my client to estimate their costs. I'll accept a range of currencies."