If possible, it's probably prudent and worthwhile to attend at least a basic handgun safety class and then a defensive-oriented handgun training class. It's not easy to know what you don't know without an instructor observing and assessing you.
Before I entered LE I thought I was pretty competent at shooting my 1911, DA & SA revolvers. I was an avid handloader and did a lot of shooting. Not any sort of competitor, but just an avid handgunner who first learned to shoot as a youngster under the tutelage of my father.
Having to shoot LE revolver quals as a young cop, for score & time, showed me where I needed improvement.
Then, after several years I decided to try and become a LE firearms instructor. I figured it was a good way to get even more training & practice, and teaching other folks helps instructors continue to learn. (Something I learned as a younger martial arts practitioner.) The basic firearms instructor class again showed me where I needed some further training and refinement.
Recurrent training over the years, including now working alongside fellow firearms instructors of a wide range of training & experience of their own, continued to show me areas where I needed ever more development.
Nowadays, younger shooters have an advantage of a lot more handgun training being commercially available ... with the caveat that "buyer beware" is still a prudent consideration. Maybe some NRA sanctioned classes for basic skills and knowledge?
Then, the acquired skills can be tested, practiced and hopefully refined by finding any IDPA events that may be conveniently located to the budding enthusiast.
Having a qualified instructor/trainer lend a hand is still the best way to get some good training and learn the difference between good & bad habits.
Having hit 60, and being retired, but still keeping my hand in things as a firearms instructor, I try to keep my skills current by taking advantage of having access to an agency range where I occasionally work. I don't get fancy, but tend to do a lot of whatever current qual/training sessions are being run, which typically means 1-11 yds. This can include shooting-while-moving, shooting & moving, multiple threat targets, judgment/decision-making by including non-threat targets, different positions (standing, kneeling, prone, supine), off-hand (also called weak-hand, if you'd rather), barricade/cover use & shooting, etc. It changes all the time. I also slip in other demanding drills we've periodically developed, or "borrowed" from elsewhere, over the years.
It still comes back to well-learned & ingrained "basics", though.
Proper practice keeps them ingrained and accessible.
I also still include shooting longer distances to make sure my "basic" handgun skills aren't rusting away (which includes handgun shooting at distances from as close as 15 yds to as far away as 75 yds using paper or steel targets). This dates back to my revolver days, when making aimed 25-50 yd shots wasn't exactly uncommon for qualifying courses-of-fire here & there.
During an instructor update class I attended a while back, they taped over the sights of everyone's service pistols and made us run a course of fire which included 50 yd targets. Everyone was able to pass this course of fire before we moved on to something else, although it did seem harder for some than others, with older, more experienced instructors seeming to have an easier time with it. (
Basics, basics, basics ... and, being older, also being able to
see the threat target at 50 yds.
)