Notes on setting up EC2 Autoscaling

Recently I had to set up an EC2 Autoscaling group through the mythically daunting EC2 dashboard. After a few false starts, a colleague and I managed to do it properly.
It turns out that to set up EC2 Autoscaling you need to set up four different things, in the right order. This is what we did:
1) Create target group: the ports are where EC2 sends traffic. You cannot change the port after creation. The disk must have same size as the base AMI you’re using (the interface lets you pick anything, but if you don’t re-enter the same disk size as what the AMI has, it will fail on launch).
2) Create load balancer: associate with a security group; You can edit later to which target group it points to. No need to register targets on creation, do it from step 4) directly.
3) Create launch configuration: set up the template for autoscaling group (AMI, disk size, security groups).
4) Create autoscaling group: assign target group; ports are where it receives traffic from. When creating autoscaling group, choose the target group.