After castling, it is generally proper not to move the Knight's Pawn that is before your King, until you are obliged.
In a diagonal line of Pawns you should endeavor to preserve the Pawn at the head of them. Pawns, when united, have great strength; but when separated, their power is sensibly lessened.
A passed Pawn is mostly serviceable when supported by another Pawn.
A doubled Pawn is not in all cases a disadvantage, especially if it is united with other Pawns. The worst kind of doubled Pawn is one on a Rook's file; while the most advantageous is the King's Bishop's Pawn doubled on the King's file, because it strengthens your middle Pawns and opens a file for your King's Rook.
The Pawn being less important than a Piece, it is usually better to defend with it than with a Piece. For the same reason it is likewise better to protect a Pawn with a Pawn than with a Piece. No Piece can interpose between the attack of a Pawn, it can therefore frequently check the King with great advantage.
Be cautious generally of advancing the Pawns far on either side, till you see on which your opponent castles; and remember, when approaching the end of a game, where you have Pawns, or even a Pawn, against a minor Piece, that you may win, but that your opponent, except in very rare cases, cannot, and that two Pawns in any situation can protect themselves against the adverse King.
MAXIMS AND ADVICE FOR AN INEXPERIENCED PLAYER.
There is nothing that will improve you so much as playing with good players; never refuse, therefore, when any one offers you odds, to accept them: you cannot expect a proficient to feel much interest in playing with you upon even terms, and as you are sure to derive both amusement and instruction from him, it is but fair that he should name the conditions. It will soon happen that you yourself will be able to give odds to many amateurs whom you meet; when this is the case, avoid, if possible, playing them even, or you are likely to acquire an indolent, neglectful habit of play, which it will be very difficult to throw off.
Never permit your hand to hover over the board, or indeed to approach it, until you have completely made up your mind what Piece to move; a contrary habit begets a feeling of indecision that is fatal to success. Play invariably according to the laws of the game, neither taking back a move yourself, nor allowing your opponent to recall one. Do not exhibit impatience when your adversary is long in making his move. His slowness is a tacit compliment to your skill, and enables you to play with proportionate quickness, because while he is meditating on his next step you can take advantage of the time to consider what shall be your rejoinder; besides, it is absolutely necessary for every one desirous of excelling at chess to play slowly. A fine player examines occasionally from five to twenty or more moves on each side: can this be done in a moment? It is easy enough to play quick against inferior play; but against equal and very good play one cannot play quick without losing.