karder wrote:Getting some good training from a reputable instructor can go a long way and will introduce you to some different techniques and scenarios.

I can only provide some lessons learned based on my own mistakes in that regard.
Way back when I was (a little) younger and (a little) fitter, I drew up something of a firearm training bucket list and decided that, over a period of years, I wanted to take classes from a number of the biggest-name instructors/schools I knew of, like Gunsite, Thunder Ranch, Gabe Suarez, Mas Ayoob, John Farnam, Paul Howe, Kelly McCann, Craig Douglas, Brian Hoffner, Spec Ops Systems, and others. Looked good on paper, but I didn't get as far as I'd hoped.
One failure was inadequate research. There's really no standardization around the country in defensive firearm training, but there are a lot of great schools and instructors. Some will accept a completed basics course from a different instructor as evidence of competency in order to take a more advanced course, but many will not. Taking a "Gun 101" class from multiple instructors ain't as helpful as an intermediate or advanced course from multiple instructors. I'm proof.
Recommendation: Do extensive research and make a detailed roadmap if you plan to do more than take an introductory course. The classes, ammo, and travel and lodging (if required) ain't collectively cheap, so go in understanding exactly what are and are not "transferable credits" in order to maximize the training. If you really want to take an intermediate defensive handgun class at Gunsite in Arizona, it'll be pretty deflating to learn that the introductory course you just took won't allow you in and that you'll still have to take Gunsite's introductory course.
If someone is completely or mostly new to handgunning, the NRA courses are, comparatively, inexpensive, quick, often local, and a solid start. Money well spent. A lot of independent schools/trainers, though, won't take an NRA certificate as evidence of basic competency to step into their more advanced courses; most of those non-NRA beginner courses are pretty active two-day affairs. The NRA breaks things up into smaller chunks.
Once you've had some training, go into the next course as if you really hadn't. All gun safety lessons are ingrained and do carry over, of course, but otherwise the biggest favor you can do for yourself--especially if taking a class from a new-to-you instructor--is to keep a completely open mind. Be a sponge, and never even think, "But I was taught to do it differently," or "I've always done it this way."
Even if never spoken, those resistance thoughts become a huge impediment to absorbing the instruction you're paying hundreds for. And spoken, it engenders no love from the instructor...or other students in the class. Doesn't mean not to ask questions. Just don't let past training or knowledge interfere with what's being taught. Pretend you're a college student attending a lecture by a Nobel Prize laureate. Set any preconceptions aside and soak up as much info as you can.
Somewhat related and something I stumbled on accidentally. I've never had any training scheduled for a full day not go at least eight hours; I've had many, especially if including low-light instruction, go 10 and even 12 hours. Not necessarily the best scenario for retaining new information (a subject for later; I'm reading a book right now that, in part, addresses that very issue). At first I'd go back to the hotel, do a quick clean and check of the firearms used, shower, and collapse to sleep like the dead.
Kicking myself for not thinking of it sooner, I started carrying a digital audio recorder with me. If there was a lecture portion of the course, I'd ask if I could record it for personal reference only. Most times I got a "yes." But then I'd also use it as soon as possible after a day was over to record what was taught, what we did in range training, what I learned...takeaways I wanted to remember, because your retention just ain't great if you're exhausted and sleep on it.
Once the course is finished and you're on your way back home,
that's a good time to bring past training back up. The digital recorder can be helpful again. Do a compare and contrast. What techniques/concepts were new, similar, or different. If different, how, and what supporting information backs up each? Which do you think are the most logical and plan to adopt? In fact, your preference may end up being a hybrid of different techniques that you think makes the most sense. The result is you have not only a solid understanding of
what to practice, but
why it's the best thing to practice.