This question is too broad as is. A good place to start is looking at your cost breakdown which is available in the console. For example, if it shows your highest spending is on EC2 then you should assess your instance types and use case. If your S3 spending is high, assess what you're storing; if any of it is low-access, assess the storage class you're using and consider glacier. These are just two examples of two services and how you might address high spend; AWS has countless services so it is highly dependent on what you're actually using. So figure that out and then google reducing AWS spend for [specific service name]. Good luck!