You only get better at 1ticking by being constantly thrown into the situation over and over, just like anything else in this game. Dont worry about it, eventually you'll get more comfortable with it.
As for the supplies; I was a lot like you when i was doing Inferno, and i'm here to tell you-
USE YOUR GODDAMN SUPPLIES!
There is some nuance to this, personally i'd rather restart if i had to choose between brewing at wave 30 or planking, but especially once you hit around wave 50-ish, do not hesitate to click yellow. Waves 50 and up are when shit really starts to hit the fan, and these are the waves that you saved your brews for in the first place. Good luck