With Terraform as my preffered tool, but CloudFormation, Ansible, whatever floats your boat. Repeatable, organised infrastructure.
No more hacky scripts and hoping that one guy who set things up doesn’t get hit by the wrath of Zeus. With Infrastructure as Code (IaC), all of your infrastructure is auditable, visible, understandable, repeatable, and repeatable.
The same networks, auto-scaling groups, load balancers, etc. come up on every run, so if something goes wrong with a service, it can be back up and running in minutes.