Microsoft hosts a lot of blogs covering every service area and aspect of Azure. One of the most under-used (from what I’ve seen) is for Cost Management.
This is a detailed and information rich source that I strongly recommend you follow. Not only will you learn about Cost Management best practices, you’ll also learn about cost savings opportunities in specific Azure services, such as reserved instances for Azure SQL.
You can follow the ACM blog here.
Azure FinOps 