Although not even the world's best coach would be capable of providing a written list that could guarantee success, the following 10 points are core things to remember when attempting a perfect freestyle stroke (also known as the crawl).
With luck and perhaps a little poolside advice from another swimmer or instructor, these 10 items should ensure that you have the basic freestyle stroke mechanics down pat. You may already have several of them mastered, or you may just be starting to learn how to swim. Either way, there's no better time to make technical improvements than now.
Take one tip per week and only concentrate on that specific aspect of your stroke. The next week, choose to work on another tip, but remember the one you practiced the week prior. In 10 weeks time, not only should your stroke be markedly improved, but the improvements will feel natural and require less concentration because you added them together slowly over the course of a few months.
Rather than information-overloading yourself with too many things all at once (a common problem at weekend-long swim clinics), you will have taken several months to carefully master all the different, basic elements.
1. Head Position
Body position in the water is the most important component to swimming efficiently, and the position of your head dictates the position of the rest of your body. Look forward, with your hairline cresting the surface of the water in front of you (if your hairline is receding, then make sure that your forehead is just below the surface!).
Your neck and upper-back muscles should be relaxed, and assuming that your body is parallel to the bottom of the pool (as it should be), your head should be cocked forward about 45 degrees. If you "bury" your head into your chest, it will serve as a 25-pound form of resistance. It also will alter your body position by forcing your upper body to dive down and your hips to breach.
Conversely, if you look forward too far, your face will serve as resistance and your neck and upper-back muscles will tense up, causing fatigue and discomfort.
More: Body Position Basics
2. Reach Forward
With each stroke, make sure you are extending your arm to its maximum length. Many swimmers place their hand in the water in front of their head and begin their underwater pull. Instead, concentrate on placing your hand in the water about 15 inches in front of you, and then reach forward an additional 6 inches by extending your arm from your shoulder.
That little movement involving your shoulder (imagine you are standing and trying to reach for a ceiling just beyond your reach) can lengthen and smooth out your stroke for maximum efficiency.