I got very lucky in this game yesterday. I started out well, I thought, with a strong center and plenty of room for my pieces. If only I knew how to turn those advantages into something tangible. Black soon challenged my center with d5, and the center stayed fairly tense throughout the middle game. Computer analysis showed many suboptimal moves which resulted in slight advantages that swung from one player to the other.
Black traded a knight for my two central pawns, which I thought was to my advantage though the computer shows it was a good trade for Black. He probably needed to work on advancing his passed pawns to make the trade worthwhile, though. 
At left, is a typical position of the middle game. I thought for a while and moved Bf3, but the computer suggests f4 instead. Eventually I figured out I should use my extra piece to try to win trailing pawns and got into a decent position, but was very short on time. Black kindly dropped a rook with my clock under two minutes, and I barely had enough time to mate him–only four seconds to spare. Very lucky.