A perfect swimming stroke will allow you to go farther and swim more quickly while expending less energy. The best way to improve your swimming technique is to pay attention to each part of your body individually to make sure that you are moving each part correctly. For freestyle and breast stroke in particular good form is essential.
In freestyle the most important thing to remember is to cup your hands in order to effectively push water out of the way and propel you forward. In breast stroke the additional hand position to master is the gliding position. Overlapping your hands and creating a point with the tips of your fingers will create a break in the water that will allow you to glide farther and use your momentum to push you ahead.
Arms directly influence the way your hands enter the water and guide the direction of your body. They should be completely extended and aligned properly to the head and the rest of the body in freestyle and circle outward and then down in breaststroke.
In freestyle your legs should be a straight extension of your spine behind your body. Kicks should start at the hips which is more effective than kicking at your knees when your legs are completely extended. In breast stroke leg positions are even more important because for half of the stroke the whip kick acts alone in moving you through the water. Unlike the kicks in freestyle, the whip kick is powered by a bend at the knees then turns into a straight extension of your body. With either form legs should stay at level with the rest of your torso.
Improving your swimming technique is all about paying attention to different parts of your body and fine tuning each movement to create the perfect stroke.