CLICK HERE) before travel in order to enter the USA. These last for two years and are obtainable online. If you have one already check the expiry date, and remember that if you have replaced or renewed your passport since it was issued you WILL need to get a new one.
YOU DO NOT NEED a work permit. This means that any offer of a payment or fee for any private event, interview or similar may not be accepted - however a donation to the charity is acceptable.