1. Simulate payment either with value that has been set in our scenario or with incomplete value, invalid value, or duplicate value to see what happens
2. Make sure you have properly written your code to handle every possible error type
3. We suggest you to have your own log for all requests that you do and regularly examine it
4. Differentiate the payment simulation you made in test mode from the actual payment in live mode
5. Set up callback URL in test mode
6. For security, we suggest you to change secret API keys regularly in case the work flow of your server result your secret API keys stored in multiple places.