How not to be a retard when dealing with firebending?
It's more of a drafting skillcheck in that you want to run cards which give you sinks for the mana. Many of the firebending cards have their own sinks, but they tend to be pretty weak: a 1/1 counter, a 1/1 creature, 1 damage etc. This means you want to load up not just on clue-makers but on barrels of blasting jelly, which provide early fixing and then double as entirely-affordable removal.
There is also knowing that after damage, there is the 'end of combat' step in which you can still use it. Arena generally skips over this step, but it was how (for example) you could attack with a Decayed token back in Midnight Hunt, have it deal damage, then sacrifice it to something instant-speed (like, for example, village rites).
This is useful because it allows you to option-select: if you have
fire sages and expect your opponent will just kill it with a
razor rings, instead of dumping the 3 mana into sages, you can wait - either to dump it into a clue or to just not have spent the 2 mana that it didn't generate. Putting counters on after dealing damage does make you miss a damage, and your opponent can still razor-rings it in response after damage has been dealt during the end-combat step (as it is still attacking), but even this nets you 2 additional damage.
There's also knowing that, for example,
firebending student is generally a shit card in limited that you should not slot into generic red decks. But if you get a lot of combat tricks (especially the one that creates a clue) or even just how-to-start-a-riot, the card becomes a house - again provided you have suitable sinks. It becomes possible to t2 student -> t3 Cunning Maneuver -> kicked Firebending Lesson or Fire Nation Attacks or Blasting Jelly.
I suppose another good firebending retard-check is if you feel any temptation to slot
Sozin's Comet into your limited deck, you need to go back to basics.