The gold standard is a complete stretching routine before and after every run. Now let’s deal in reality.
Before most runs, spend at least a few minutes on the muscles on the back of your body—calves, hamstrings, glutes, lower back. They’re the muscles that are going to be shortest and tightest from the last several hours of your life. Active isolated stretching or dynamic stretching is the way to go pre-run. If you’ve been sitting for the last while before your run, do the Cat-Cow exercise: On your hands and knees, round your back and draw your belly button toward the ceiling while tucking your chin (cat), then arch your back and raise your gaze to the ceiling (cow). Doing a cycle of this exercise will loosen the soft tissue around your pelvis and allow you to start your run feeling more fluid.
After running, spend a few minutes on any areas that felt tight or otherwise troublesome on the run. Hips, glutes, and hamstrings appreciate a little attention at this point. Active isolated stretching is good at this time; if you’re a fan of static stretching, post-run is the time for it. If you drove to run, when you get out of the car, do Cat-Cow to help unlock your pelvis.