Some random thoughts:
- Patience is not just for (the Biblical) Job... you will find it an awesome hobby with lots of idiots, know-it-alls, mall ninjas and... maybe... just maybe... a few shrewd young and a few wise old codgers. The those shrewd and wise say very little, so turn down the blaring crap in your ear buds and listen well.
- Understanding that sight alignment is crucial: cheek weld, proper fit and aligning your eyes to the sights is key. Most people need cheek risers with scopes and don't even know it. Get the proper equipment to do the job of sight alignment. Some people can do a chin weld, but even if you are Jay Leno, your chin isn't big enough for that!
- An understanding that trying is better than supporting the Equipment Exchange: I never buy a shotgun without mounting it to my shoulder a lot just like I never buy shoes without walking the store for 30 minutes in them. If you are buying a handgun I suggest going to a rental range. Otherwise, you buy it and it doesn't work for you (polymer guns is my bane, never knew until I went to a range) and you end up lovingly getting a large trader rating the painful way (if your selling at low prices, ignore me!)
- A decent cleaning kit and knowledge how to use it on your firearm: get a basic kit, be sure it has the exact size of brushes for your gun. Learn from the CGN members that know their stuff. If you are serious about cleaning proper bore guides and one piece rods are amazing... like pie, your favorite pie!
- Ammo that works: practice, practice, practice. And safety practice should be there 100% of the time even if you are dry firing alone in the basement because repetition gains muscle memory. You also need targets you can hit and see: the broad side of a production hog farm barn doesn't help if you can't see it or see rings/lines to shoot at. The lil'piggies inside will feel safe otherwise: go for bacon and hams... not them hamming it up at your expense!
- If you are using and mounting a sling on your gun, learn how to use it: it can be used for steadying your shot, not just for slinging on your shoulder. Those who clean urinals understand better aim, a sling can help with that too!
- Actual gadgets? Bore guide for the rod, having a proper sized and knowing how to use a jag properly, anti-cant device if long range shooting a rifle, a good cheek rest if needed, and a few other I can't think of.
The best for last:
Proper fitting glasses and hearing protection. Shooting is awesome, but shooting blind and deaf sucks... a lot. Then your shooting ends up like Justin Trudeau trying to form a cognitive sentence in question period, and we all know how bad that is.