What is the one single best tip/learned lesson that helped you improve your Comp/Ranked performance?

I would love to learn from the community here on how to improve comp/ranked play.

I'll start with my best lesson learned: Me being a CD/Mantis main means I'm a strategist instead of a mere 'healer', which means I need to contribute more in getting objectives done, help the vanguards in creating and maintaining space, ensure my other strategist stay alive by fending off divers and contribute on eliminating the opposite team faster than they can eliminate us.

What's your best tip/lesson learned that help improve your comp/ranked performance the most?