Ooo, I saw 10 things and didn't click over just yet. I wanted to see how many I could guess.
Lessee. A good attitude and a willingness to learn.
A spare gun. Breakages happen and like to happen during gun class.
Lots of mags, preloaded, and a mag loader so make reloading those mags as easy as possible. Ammo for same, of course.
A hat. To protect from the sun and shade your eyes.
A good appropriate holster and a GOOD belt.
Drinking water.
That's six. Lessee how I did...
The article had more clothing recommendations. Like footwear. Expanded on the belt. And ear and eye pro and a range bag.