COST 2. How are you optimizing your usage of AWS services?
If you use application-level services, make sure that you use them well. For example, introduce lifecycle policies to control Amazon S3 usage or leverage services such as Amazon RDS and Amazon DynamoDB enable tremendous flexibility. Checks for appropriate usage include verifying multi-AZ deployments for Amazon RDS or verifying that provisioned IOPS are applicable in your Amazon DynamoDB tables.
Best practices:
 Service-specific optimizations Examples include minimizing I/O for Amazon EBS; avoiding uploading too many small files into Amazon S3; using Spot instances extensively for Amazon EMR; etc.