To achieve good account health in Amazon, there are several metrics that need to be fulfilled but some are as follows:
1. Order Defect Rate (ODR), you should keep it minimum and lass then 1%.
2. Negative feedback, you should not get too much negative feedbacks this can affect your account health.
3. Cancellation Rate (CR): Amazon expects sellers to maintain a CR of less than 2.5% to ensure good account health.
4. Valid Tracking Rate (VTR): Amazon expects sellers to maintain a VTR of at least 95% to ensure good account health.