OK I admit it - I've been exploring the Wizards of the Coast website, where I found this article with some good advice that is applicable to all kinds of boardgaming, not just Magic. Forgotten Lore: Mind Over Magic:

The great players all compete with discipline and mastery over their emotions. Any player can win if he or she gets a great draw, or if an opponent is mana-hosed. It takes a great player to overcome a poor draw to claim a victory. Within the playing community, there are many ways to describe various facets of this ability: the Jedi mind trick, the good-player draw, or most often, luck. What is seldom recognized is that good players seem to get lucky more often because of their inner game. First, they build their deck to minimize the impact of a lousy draw. Second, they play with calm discipline even when things aren't going their way. Again, the focus is not on the almighty win, but on being wholly present in the game. The distinction might be a fine one, but I believe it holds nonetheless.