The sticky covers the basics of configurations.
After that, you need to learn how to use your advantages and minimize your disadvantages. If you get in the first shot, odds of you winning go up dramatically, biggest tip I can offer there, start the fight on your terms, not theirs.
Learn 2 Play. PvE levelling play is NOTHING compared to PvP. Your foes are not computers that you can predict or trick with formulas. They are possibly smarter than you and may be better than you. Disengage your ego and learn as you play. If someone defeats you, remember how they did and figure out how to counter it the next time. It may take two dozen times but eventually, you'll get it figured out and then THEY will be the ones defeated.
Best thing: positive attitude and keep learning at the forefront of your brain. Losing the fight should not bother you. Learn from the loss and move on. A sporting player does not gloat when they win either. Every foe presents a chance to learn, be thankful for the chance and respect the foe.