Own your mistakes.
Don't complain about the dice.
Don't complain about the card draw.
Don't complain about perceived faction imbalance.
Take a long look at what happened in the game and see what you could have done differently.
Learn from your mistakes by not making them again.
If things don't go your way and your opponent got lucky despite all your best efforts, tip your cap and move on with your life, because it happens, even to the best of us.
Then demand a rematch.
If you lose again, look in the mirror.
My martial arts instructor long ago taught me what he called the first rule of self defense:
Don't be there.
You don't roll to move or decide how many cards to build as magic. If you prepare for the worst- your attacks missing and your opponent hitting on all dice but still keeping yourself in a safe spot, you won't regret it.