I didnt write this but it is exactly what I would have said if I had typed it.
-Use quality USA made ammo, such as Federal, Winchester, etc. Do not take surplus, Wolf, etc. to a class. One of the worst mistakes I see are shooters spending good money on training and then showing up with cheap ammo, and they have nothing but ammo related malfunctions the entire class. An example of this is we had 4 guys that were shooting "Olympic" brand ammo (made in Greece), and their guns were jamming every couple of rounds the entire class, this slowed things down for the rest of us.
-MASTER YOUR IRON SIGHTS FIRST. A lot of guys love optics, and in my personal opinion optics help most shooters. But before you go and buy an ACOG, Aimpoint, EO Tech, or any other optic, master your iron sights FIRST. Once you have mastered the iron sights then and only then consider moving up to optics.
-Use quality USGI magazines with the GREEN or new Magpul followers. Another thing that I do to my magazines is use the Wolff Gun springs 10%+ mag springs in my mags. If you have the time take the mags to the range and make sure they work well. Nothing worse then showing up to class with crappy mags and having your gun malfunction on a constant basis due to bad magazines.
-Learn to properly clean and maintain your gun properly. I always recommend the US Army or USMC M16A2 manual to new shooters, these manuals will show you how to properly maintain and clean your AR15. On the first day of class make sure you show up with a properly cleaned and lubed carbine. Everyday after class properly field strip, clean, and lube your carbine. In most Tactical Carbine Courses you will shoot approximately 500 per day, everyday. The guys that don't properly clean and lube their carbines will be easy to spot......Their guns usually go "TITS UP" the second day of class prior to lunch. A USGI cleaning kit has everything that you need in it to properly clean, maintain, and lube your gun.....and make sure to use the chamber brush.
-Buy a quality rifle / carbine and don't try to build one. In the classes that I have been to approximately 90%+ of the "built" guns have gone tit's up. Last year in a carbine course, the instructor took a poll. Of over 20 students, 12 or so had "built" rifles (all AR-15's) and of those 12 100% of them went tits up during the class. The rest of the guys had factory built guns and none of the factory built guns went tits up. That is not to say that I haven't seen a factory gun go tit's up, it just happens a lot less than with a gun that is built from parts from different manufacturers. Stick with the "Tier 1 manufacturers" ie. Colt, Bushmaster, and Rock River Arms as a general rule.....and make sure the gun has a chrome lined barrel.
-I always recommend having a gun that has 1,000 rounds through it prior to coming to class. If there are any problems (ie. loose gas key, etc) they will usually arise in the first 1,000 rounds. I have seen some guys show up to class with a brand new gun and put 1,000 rounds down range without a problem, and I have seen other brand new guns that have some teething problems the first day because they are brand new, but start settling down the second day. Along with this "break in" period, it also let's the shooter know what ammo and mags the gun does or doesn't like. If you shoot the first 1,000 rounds with Federal American Eagle .223 and 5 USGI mags with no problems, then take that same ammo and those same 5 magazines to the class.
-If you have access to a second AR, take it to the class. If carbine #1 goes tit's up, you've got a back up.
-If you are new to AR's get a SIMPLE carbine and shoot it in the class.....Many times I have seen shooters show up to a class with all kinds of crap hanging off of their guns and all those accessories give them nothing but problems. Start off with a simple carbine with iron sights, take the Tactical Carbine Course, learn how to operate your gun proficiently, then add accessories as you need them
-Make sure you have a good sling, I always recommend a 3 point sling to new shooters, and you will probably need a 3 point sling, because most likely you will be doing transition drills (transitioning from your carbine to your pistol)
-Remember keep it simple, take a good quality, factory made AR (and use the IRON SIGHTS), good quality USA made ammo, good quality USGI mags, a 3 point sling, a USGI cleaning kit, knee pads, plenty of water, and an open mind!!!