As you can see everyone has an opinion of what a good player is, some also became examples of not so great players
Learn your rotation as best as you can but also learn about the class like priority systems, what buffs should be used together, also how well your job works with other ones (synergy)
Be helpful to those who do not know and except advice even when it's snarky which is what it is majority of the time lol
Last but not least do not get consumed with others dps unless it motivates you to do better...always exit gracefully lol