How do I play against the falkbeer countergambit?

How does white respond after 1.e4 e5 2.f4 d5?

Opening Principles:

1. Control the center squares – d4-e4-d5-e5

2. Develop your minor pieces toward the center – piece activity is the key

3. Castle

4. Connect your rooks

Tactics...tactics...tactics...

Pre Move Checklist:

1. Make sure all your pieces are safe. 

2. Look for forcing move: Checks, captures, threats. You want to look at ALL forcing moves (even the bad ones) this will force you look at, and see the entire board. 

3. If there are no forcing moves, you then want to remove any of your opponent’s pieces from your side of the board. 

4. If your opponent doesn’t have any of his pieces on your side of the board, then you want to improve the position of your least active piece. 

5. After each move by your opponent, ask yourself: "What is my opponent trying to do?"

Opening principals are going to be more helpful than lines.

Don't believe me? Here, I'll dump some lines from a database with no explanation. Not very helpful is it.

3. exd5 is the most common reply and then black either choses to push with e4, take with exf4 or offer a pawn with c6.

Here's a game I finished recently where I was the black side.  White seems fine until he decides to give me piece odds and then he's not so fine.