I've been running a long time, and i've never found or subscribed to any wierd breathing techniques (especially "in through nose/out through mouth" crap)...but I can tell you this...
a warmup jog of a mile or two followed by stretching that involves some deep, lung expanding breaths will give you a great edge on your run. oxygenate your body as best as possible and concentrate on relaxing. Stretching out real good while breathing deep breaths will get oxygen to the crevices, nooks and crannys in your body, while prepping your lungs to be expanded to their max for the run (at least the end of it!) When running, concentrate on opening your lungs with good posture and staying relaxed, same time don't be afraid to breath hard and SUCK AIR...your body needs it..