There are a few exceptions, but you only want to overheat using the Flamethrower skill. Use cooldown to manage heat between wildfire windows, staying between 50 and 100 heat.

Generally:
After overheat-> 3 GCD shots -> Hotshot (reapply while GB is down to save 30 potency, since you're replacing a non-heated shot here) -> GB+Barrel Stabilizer->use reload, rapid, and cooldown to stay between 50 and 100 heat.

https://docs.google.com/document/d/1...it?usp=sharing

Here's a good MCH guide to read up on