Raw experience is the single biggest thing. I am so used to playing tournament matches now that at the last Smash and Coffee, I started laying Bloodhawk in the finals and forgot it was the finals.
As for not being tired, do math. All you really need to do to "wake up" is to activate your prefrontal cortex. I personally play the quick math games on Brain Age (no lie) before every set.
It also helps to not play a lot in a row, and not have too long before a match. Play a few matches, wait about ten minutes, then play a few more if you are waiting.
Also, never take a nap.
A neat trick that isn't math related is to name the colors of things. You can try it right now, it works.
Look around the room, and float from one thing to another and say the color in your head. Yellow... red grey white black blue green red orange light blue black green red silver... so on so on, and after a few seconds your brain will be going "SUP?!"
