Evaluate Your Position
Look for standard positions that are played repeatedly in chess games. Use your knowledge of fundamental tactical and strategic principles to evaluate the position. Look for any tricky moves that you or your opponent may use. Consider imbalances in where the pieces are located and the squares they control. A piece being centralized and having mobility gives it a great advantage.
Formulate a Plan
Use your evaluation to create a plan. Every plan needs to be realistic and have specific goals. Think ahead as many moves as possible. If your goal is to control the center, you may want to advance pawns and position bishops, knights and your queen in better locations.
Stymie Your Opponent's Plans
Try and consider what your opponent is planning. Make sure you aren't proceeding with a plan that your opponent can quickly counter or make irrelevant with an attack on an important region of the board that you will have to respond to. If your opponent has immediate threats, you may have no choice but to deal with them.
Modify Your Plan
Almost never will you be able to follow through with a single plan from the beginning to the end of the game. Positions are constantly changing and you need to modify your plan frequently. Significant changes may require that you completely abandon your plan and come up with a new one.