During the early part of the game, try to control the center area of the board. Move pieces into the center, or move pieces into position to protect the pieces in the center.
The most common opening moves are to move the king's pawn or the queen's pawn two squares forward.
As you move your pawn structure forward, try to keep the row staggered, so that the pawns to the rear protect the more forward pawns.
Don't overreach - for example, don't move your bishop into an aggressive position by itself on your opponent's half of the board, where a simple pawn move will force it to retreat. Move your forces out steadily and evenly.
Sacrifice a less important piece in order to take a more important piece of your opponent's. Generally speaking, the order of importance of pieces, from most to least important, is queen, rook, bishop, knight, pawn. Some experts consider the knight and bishop to be of about equal worth. The king is not included on this list since it can never be taken.