I am using elastic 7.4. I am wanting to put in my licenses userids and passwords. Also setup AD authentication and encryption of the connections. Last time on non prod servers i had an issue where i enabled security and I was lock out of the whole cluster. I do not want to experience that this time. So what is the proper order I should use to complete my tasks?
We just released 7.5, so make sure you upgrade 
https://www.elastic.co/guide/en/elastic-stack/current/installing-elastic-stack.html is the best place to start, it links you to each product and the best path.