Well you have to run every day. At lest 5 to 10 k. Use a heart rate monitor for the first couple of months and don't go above your aerobic range (65% to 85% of your max heart rate). Do that for a couple of months starting out at 5K every other day for the first two weeks, then 5 k a day every day for two more weeks, then gradually increase your volume until your running 45 K on the 8th week (5 x 5k and 2 x 10 K). Then start integrating speed work into your schedule. On the third month still run 45 K/week but do 4 X 5k and 2 x 10 K in your aeroblic range and then do 1 5K at race pace (aka anaerobic threshold, 85% to 95% of your max heart rate). At the same time your doing this, keep track of your caloric intake. Try to keep at or below 2,000 calories a day. If you follow this program you'll see a significant improvement in your per mile rate in a 5 K. The important part is to be disciplined the first two months. Run every day per the schedule and do not exceed the upper or lower limit of your aerobic range. The purpose here is to develop your aerobic metabolic pathways so that you use oxygen more eficiently, imrpove over all fitness, develop sound biomechanics and develop both capilary beds and neuromusculer patheways in you skeletal muscles and lose excess, nonfunctional, body weight.
After the third month maintain the schedule of week 8 but drop one of your 5K aerobic runs as a rest day. Preferably the day after you do your race pace 5k.