Metering
How can you tell you are at the right levels when you only have tiny little meters? Metering is very important. Unfortunately only high-end equipment seems to have accurate, large metering. If it had large meters, it would be a lot more expensive.
But, there are cheap solutions. If you work on an analogue board, go to an army surplus place, or even radio shack, buy some meters cheap, and put them on the left and right bus of your console. A little bit of wiring, a couple of bucks, and you’ll be forever grateful you did it. If you work on a DAW, get some metering software. There are cheap ones and expensive ones; everything is better than none at all. (I use Spectrafoo software).