Old, but good. Gets a Rook and knocks your oponents confidence early on in the game. Works OK but perhaps at that stage the Horse you will probably lose is worth more than the Rook you gain. The minor pieces are worth more than the Rook at that stage, You pay your money and make your choice!
What????
....ehm...i agree with Michael-G 
The next rule is to move your pieces to their best squares.
I hope i am not annoying.I really don't get this.Move pieces to their best squares?Do you mean if a piece has X number of possible moves,then move it to the best possible move?
The main idea is the diagram below! I offer these moves to the starters because I'm trying to teach them how to combine their forces to attack f7. Why f7? Because it gives the cheesiest mates ever. (Starters should start with thinking how to mate the enemy king while defending their own, this is the first rule)
Thanks Yavuz!
I understand the meaning of the first 3 moves,but 4.Ng5 isn't riksy?
4.Ng5 is indeed risky. A very double-edged move. Black as equal chances in complex positions with best play, however he needs to know how to react.
The main line is 4...d5 (black radically blacks the bishop diagonal) 5.exd5 Na5!(kicking the bishop away from that dangerous diagonal, the attack on f7 has now failed) 6.Bb5+ c6 7.dxc6 bxc6 (white has gained a pawn but black has compensation thanks to his very open position which allows fast development). Countless variations start form here (and both sides have earlier alternatives. Worth knowing is that 5...Nxd5?! is reasonable looking but in fact risky since 6.d4! (6.Nxf7!?, the notorious fegatello attack, is exciting and interesting but definitely weaker). Now white threatens a powerful sac on f7 in improved circumstances. This was once considered close to winning for white, and even if theory has found a way to obtain a playable position with black the variation remains very favourable for white in practice.
However i don't think you should play Ng5 at your level. It's a move which requires a considerable theoretical backup if you don't want to be lost as white after 15 moves. I would rather play the romantic 4.d4, or O-O, or the modern d3. The basic theme of the opening is the attack against the weak f7 spot, and this is true even if you don't go immediately for the throat with Ng5.
Here is a scotch The Benefits are you get your pieces into the game and you trade of quickly to get in a early endgame. That is what the Scotch is for.
Old, but good. Gets a Rook and knocks your oponents confidence early on in the game. Works OK but perhaps at that stage the Horse you will probably lose is worth more than the Rook you gain. The minor pieces are worth more than the Rook at that stage, You pay your money and make your choice!