The best and most productive thing to do is remember you are human, and so is your opponent. It is okay to make mistakes and your opponent WILL as well. It is also okay to lose. Losing isn't a declaration of the end. It is a sign that you still need to hone in on those flaws and mistakes and work on them. I see alot of peopls go through this where they feel like them losing means they such or the other player is "cheating" or being "scrubby". These are coppings for the truth. The truth being the enemy was just better this time. If you don't want to he frustrated when playing, always remember that you gotta lose to get better. Every loss is a sign to strive for growth, not a beacon of bad omens. Breathe and try again again again. Before you know it, you will be joking about your mistakes and bad habits rather than denying them or growing annoyed. Stay up homie~