Get a rescue cert before anything else. It's what I recommended to all my students. I even tailored rescue skills workshops for those who for whatever reason did not feel ready for the full rescue class.
Rescue, IF TAUGHT CORRECTLY, will open your eyes to how crap goes south before you even get in the water. And before you go taking a class that opens you up to more risk, including AOW type classes and deep classes, you'll want the extra caution that comes with seeing problems before they become something life threatening.
My second book is all about Advanced Training beyond Basic Open Water and how to choose what to do.
A sampler AOW taught strictly to standards where it's just one dive in a few specialties that does not give you real new skills and knowledge is good for one thing. Lightening your wallet.
Find an instructor who makes you earn that card and has requirements you need to meet before you take the class. AOW should not be about remediating deficiencies from your OW class.
I required my Advanced students to be able to do basic skills neutral and horizontal without changing depth by more than 2 feet before starting the class. By the end of it the goal was to get that down to less than a foot.
Some rescue skills were always included and I picked the dives. No fluff stuff. Each dive built on the one before it. First day first dive was Advanced Skills that included DSMB deployment, stage/pony bottle use, non silting kick introduction. 2nd dive was UW Nav, 3rd was night/low vis. 2nd day 1st dive deep to no less than 90ft. 2nd dive search and recovery or wreck into. 3rd dive Buddy Skills and Assist.
All of them are outlined in detail in the book. If you are interested it's called
SCUBA: A Practical Guide to Advanced Level Training and is available on Amazon in print and Kindle formats.