Don't allow distractions in your reloading area.
Don't mix brass headstamps OR weights.
Wear safety glasses - always!
Keep all sources of ignition away from your reloading operation. (cigarettes, candles, lighters, etc)
Always check powder level in your cases after charging and before seating bullets.
Never keep more than one type and number of powder on your bench at any one time. Ditto for bullets/weights.
Recheck your scales each time you start a loading session.
Never load a cartridge using your memory, record good loads in a book and look them up before proceeding - every time!
Don't forget to prime your cases before charging them with powder.
Never check a loaded round for fit in your rifle inside your home unless you have removed the firing pin first!!
Always run all your hunting ammo through your rifle before taking it afield.
Just a few. There are more, I'm sure, but not at the tip of my tongue just now. Regards, Eagleye.