Tactics and blunders decide the game
The chess saying goes "The winner is the person who makes the second to last mistake." This is certainly true in the following game. Both sides had chances to win, but both blundered back and forth, missing hanging pawns and simple tactics.
Review the game below and learn:
1. Common d4-c4 ideas, like dxc4 and Qxd4.
2. How to save tempi by not acting until forced and not forcing things that will happen anyway.
3. How to think when your king is attacked.
4. How to take advantage of castling mistakes.
So remember: Don't trade away the two bishops when the center is going to be opened. Don't go after the bad bishop when you can take off the attacking, good bishop instead. Open the files and diagonals leading to the enemy king when you can. Then put pieces on those lines.