1 Not warming up before stretching. Because stretching cold muscles increases your chances of injuring yourself, you should always warm up (i.e., perform activities that will increase your body temperature enough to "warm" you up sufficiently to safely begin exercising) before stretching. Contrary to popular belief, stretching is not a warm-up.
2 Not stretching the muscles you're trying to stretch. Too many people don't stretch what they think they're stretching because they don't perform their flexibility exercises properly. More often than not, either they don't know how to do a particular exercise properly, or they make an inappropriate adjustment in their body position when stretching.
3 Not watching how much pressure you place on your ligaments. Unfortunately, some people stretch their ligaments too much (rather than stretching their muscles) when performing stretching exercises. As a result, they develop excessive ligament looseness. As such, when you're stretching, you should always avoid holding your joints in a position that places too much weight or pressure on your ligaments.
4 Not watching how much weight you place on your joint capsules. While stretching, if you place more weight on your joints than they can safely stand, you increase the likelihood that you may damage them. Accordingly, you should avoid activities that can injure your joints, such as standing toe touches.
5 Not performing a balanced stretching regimen. To avoid the consequences of stretching unequally (e.g., the muscles that receive inadequate attention tend to tighten and shorten, causing such notable conditions as rounded shoulders), it is essential that you don't stretch in one direction without balancing out that effort by also stretching in the opposite direction.
6 Not performing each stretching exercise slowly and smoothly. You should avoid using fast, jerky, or bouncing movements when performing stretching exercises. Doing so may force your muscles to stretch to an unsafe range of motion before your nervous system has time to protect them by signaling your muscle(s) to contract.
7 Not stretching to the point of maximum extension. When you stretch, you should move your body or body segment at a controlled speed through its maximum range of motion. You reach this point when you place a mild-but not painful-stretch on the muscles. On each subsequent repetition, you should attempt to go a little bit farther, while again avoiding pain and overstretching.
8 Not performing an appropriate amount of stretching exercise. A certain degree of subjectivity exists concerning what constitutes too much or too little stretching exercise. As a rule, it is recommended that you perform stretching exercises for each of the major areas of your body. ACSM recommends that individuals perform static stretches with each stretch being held for approximately 10 to 30 seconds each. Generally, static stretches are preferred because the risk of injury is low, and they require minimal time and little assistance.
9 Not stretching often enough. At a minimum, most fitness experts recommend that stretching exercises should be performed four to five times per week, and preferably daily. As a rule, because most flexibility gains are (far too) easily lost, the basic rule of thumb is that you should stretch often.
10 Not understanding that being flexible is not synonymous with being in good shape. Flexibility is just one of the essential components of physical fitness. As such, you should combine aerobic exercise, strengthening exercises, and adherence to sound nutritional practices with your stretching exercises in order to "attain and sustain" a desirable level of fitness.