Try to use it when you expect a non LK OR LP at a focus attack distance. If they are fast enough to react they will most likely jump back. If they attack as soon as it hit the focus and absorbs release and you may get a crumple. If you do get a crumple dash forward and punish.
You can also use focus as a bait for a reversal. When you get a knockdown focus so it seems like you will hit when they get up, but instead of hit cancel it and backdash. This works sometimes as some will reversal and some will not. If they don’t take advantage of this. Keep charging it and as soon as they get up they get hit by a focus (If you time it right) and then dash up and punish.
You can also use it as a anti-air. If they jump at you charge and they may attack. If they do release and punish, but this all depends on your timing.
You can also just use red focus when in a sticky situation like a corner. Some players keep hitting and you get em. I don’t recommned fully charging it though. Alot of people are getting used to it so you gotta do it fast.
You can also use red focus in a combo.
Hope this helps!