If I were black, I would take the bishop with the pawn, forcing the queen to retreat or take the pawn. And then I would take knight using the queen, protecting my bishop from white's queen if the white player decided to take the pawn. xD
Dxc4 was a bad move, whenever a bishop's square get's block it's bad.
Black lost a serious chance to win when K was on E4.
The last moves were really bad and it seems that the game ended.
One of the main things you need to keep in mind is kings safety(Castle) and moving those pawns(ie, pawn e4) aren't good at all, and if you are white while using that opening, you should concentrate on white squares rather than black.
Never let your opponent diffuse your castle.
Other than that, do calculations when a knight is near your king,especially if there are pawns around the center of the board, I observed voltrons game it seems that there were little traps you could come up with but I realized that I would have to edit the whole game if so as it was bad after both parties traded queens.(too early = worse for black, waste of move while white got an extra chance to develop)
No prob, the idea was to distract away the queen from there so we could attack that file which is one of the weakest point for players.
Our opponent was trying to pull a 2-3move fancy trick to finish the game early, the problem of that trick is that if plan fails, you would loose a good position and he will realize that all he did was moving around while white developed his game with ease.