This... and find a GOOD defensive shooting instructor right away who can analyze your technique. That way you can crush bad habits as early as possible and lay a solid foundation to get your building blocks up to speed quickly. You'll enjoy the learning process much more when you have a good starting point. You might even consider doing this BEFORE you buy the gun, as you may discover you didn't buy what was going to work best for you and you'll end up spending more on a new search for your holy grail (which isn't all bad.... I mean, I maaaay have more than one Busse, Swamp Rat and or ScrapYard in the safe).
Thanks for taking the responsibility of your own self preservation seriously.
Good luck to ya and stay safe,
Mike
Great points here!