They really are hell!
The biggest piece of advice I can give is to not try to camp fire weather, just try to catch Firesday and plan around it as much as possible. Obviously try to team up with people as much as you can - I still see lots of shouts for fire trials.
Actually, wait, no, I lied about that being the biggest piece of advice. After the initial four trials (starting on Trial 20, which is the one you're on now), dagger and sword fire paths merge. If you can hook up with a BLU Charged Whiskering mobs in Abyssea, you can knock out trials ridiculously fast.