If I were to give some advice to my younger self ... and thought I might listen ...
More attention to practice firearms training and realistic practice. Don't follow the herd.
Focus as much effort into practical firearms training & practice as you do in the martial arts. Learn how to apply arts training to firearms use, sooner.
Try and get into armorer training earlier.
There are more use calibers than just .357 Mag, .44 Mag & .45 ACP.
Don't bother with boxes and boxes of holsters, but focus on the smallest number of them that fit the greatest variety of intended, practical roles. Then, learn how to inspect & maintain them.
Spend more time 'improving' the shooter, rather than obsessing over trying to improve a gun that's already demonstrated its reliability in anticipated circumstances.
Don't get rid of the original Ruger .44 Mag semiauto carbine or the Mossberg .444 Marlin!!
If a pistol magazine can't be restored to reliable functioning with a simple follower and spring replacement, get rid of it and replace it with another one. Questionable magazines aren't worth the time invested in pondering what's wrong beyond the simplest and most obvious answer. Nobody needs boxes of questionable magazines.
Don't overthink armorer repairs and maintenance.
Don't over-think firearms cleaning & lubrication. Plan lubrication around the intended roles and environmental/operational circumstances. Don't look for a snake-oil answer to a simple question.
Unless someone is standing on a range and consistently demonstrate what they're talking about, be wary of self-proclaimed 'experts'.