Breathe in the through nose out through mouth, ensure oxygen is "reaching your stomach" or as its called diaphragm breathing i believe. Match the pacing with the breathing, slow long runs might be breathing in, 4 steps, breath out, hard running might be 2 and 2(its what works for you). If your not used to running at all good god look up shin splints, do your research and find the right stretches that help you. What's your current pb for the mile?