I like to use more than one deck. All of them are mono color, and range in the red/black/blue. I like to change playstile and strategy, as Using everytime the same card turn out boring to me.
The strategy of my deck are:
Black, a deck based on a "swarm" style, full of little and fast played monster easily powered up with a lot of +1/+1 to turn them into an horde of resurrectable monster
Red, a deck full of magic that directly inflict damage, big monster, and way to produce high quantity of red mana. Kind of a powerhouse deck.
Blue, based on the old dark steel season... I;m giving it only some little change over time... But the core strategy is still rounded on my platinum angel [love him]