Doing deep stretching before a run isn't a great idea because you're not totally warmed up and could end up tearing a muscle. In lieu of this I like to do a little light stretching, just to wake up my muscles before a long workout.
Here's a gentle stretch to try that I'm sure you've done a million times, but if you do it while tying your sneaks, it's a great way to kill two birds with one stone. Stand with your feet three-feet apart. Turn both feet in the same direction so you can focus on one hamstring at a time. After you tie your shoe, keep your torso folded over your thigh and tuck your chin. Stay like this for a good 30 seconds or more, and then switch sides. If your hamstrings are too tight then prop one foot on a table or chair. You can also do this by sitting in a straddle position. After your run, untie your shoes like this for another stretch.