How we reduced AWS spending by 80% in one month?

Over the last few months our AWS cost had been going up, so we created a plan to optimize our spening as much as possible.

After implementing the optimization plan, we were able to reduce our spending by 80%.

Here is a summary of the steps we took to get there:

Created a directory of all the resources and how they were being used.
Added tags to those resources to identify environment (dev, qa, prod) and the project name.
We used the Billing & Cost Management Console to identify areas of opportunity.
Created a projecy plan with specific tasks and owners and kept track of the progress.
Repeated steps 3-4 until we reached an acceptable threshold.

Some examples of the actions that we took:

Simplifying architecture to remove unnecessary elements,
Down size EC2 instances with low utilization.
Consolidate compute resources to increase instance usage.
Created and scheduled lambda functions to auto-stop EC2 instances during off-hours.
Setup alerts & budgets to be more efficient moving forward.