Migrating to Ansible

I wanted to see if anyone had some tips on how to migrate a current production environment to ansible? Currently ~30 servers are running in AWS. A few autoscaling groups that come up from golden ami’s. Ive been playing with ansible, used it to deploy a graylog cluster easy enough. Now that Ive seen what it can do, I would really like to start using it to manage my current servers but Im not quite sure how to start. Has anyone else had to introduce ansible into an existing setup, and if so, how did you go about managing your folder structure? How did you start figuring out what needed added to your playbook in a way that didnt interfere with what was already existing? I know 30 servers is not too large, but there are a few that I can not just trash/recreate because their are domain controllers, or Atlassian boxes.

Thank,s