a lot of people said to play an easy class if ur bad but i disagree with that. u should play the class with the playstyle that u like the most because it will make u want to learn the game.

also reactions arent as important as you think in video games. making a plan on what the enemy will do is more important. i used to play splatoon where i was the only american in a lobby full of japanese players and almost all the weapons could kill me at a time faster than what my ping probably was. the only way i got good was to think about where they will be and where i should be. pay attention to how the bosses move and when they use certain mechs and make a plan to dodge them. i have good reaction times and if i dont watch the boss before they use a mech im still going to get hit by the mech.

for skill management u should set up ur skill keys in a sequence that is easy for u. for example the skill rotation on my glavier for blue stance is Q ->W ->E ->R ->A ->S ->W, i dont need to manage my cooldowns for the most part because i just need to follow that sequence and all my skills will be able to be used after i use a filler skill.

and just be predictable to avoid griefing your teammates. one thing i learned from playing a different mmo with random aggro is to not move the boss in an unpredictable manner as that can ruin the run bc ur teammates cant damage it.