Common stretching techniques to improve flexibility include static, dynamic, and proprioceptive neuromuscular facilitation (PNF) stretching. Static stretching involves holding a stretch without movement, which helps elongate muscles effectively over time. Dynamic stretching, on the other hand, incorporates movement and is often used as part of a warm-up to prepare muscles for activity. PNF stretching combines stretching and contracting of the target muscle group, which is highly effective for increasing flexibility. Incorporating these different techniques into a fitness routine can enhance range of motion and overall performance in physical activities.