Strategy

You should know the value of each chess piece. For example, queens do a lot more than bishops. An approximate value scale would be pawn=1, knight=3, bishop=3, rook=5, queen=10, king=infinite. Although the knight and bishop are of equal value, the knight if more powerful in the beginning of the game when the board is crowded, while the bishop is more powerful towards the end where the board is less congested. Knowing these values is important because you'll know what to do if you have to decide between losing a pawn or a rook (you're better off losing the pawn).

Because you don't want to risk losing valuable pieces early you should take your time before bringing them into the battle- especially your queen!

The middle four squares on the board (d4, d5, e4, and e5) are the most important squares on the board because they let you control everything that's going on. So it makes sense to get control of the center squares. It's usually a good idea to open the game with one of the center pawns (king's or queen's), moving forward 2 squares.

Don't just move a piece for the sake of moving it. Have a plan and think about the repercussions of moving a particular piece.

Because knights can jump over pieces they make good attackers (especially in the games beginning). So don't be shy about bringing them out early. In fact they should be the first major pieces that you bring out of the back row- before the bishops!.

Lose your king, and you lose the game! Make it a priority to castle early to properly safeguard your king.

Try not to move a piece more than once in the opening, unless you can make a capture or gain something important. You don't want to start attacking until most of your pieces are developed.

If a column has no pieces at all (either yours nor your opponent's), try to put a rook there.

Try to avoid having two or more pawns in the same column (which is very common if you capture a piece with a pawn). If it's the only way to make the capture then definitely do it, but if you can think of another way go with it.

In general you don't want to develop your pieces exclusively on one side of the board (left or right).

An attack should never be launched until there is sufficient force in the field to carry it to a successful conclusion. Premature attacks almost always backfire on the attacker! Along with this strategy, you should not play a piece beyond its 4th square, until you have the other pieces ready to back it up as it proceeds into enemy territory.

Good Luck!