Closely related to the "How much should I increase my mileage" question is "How often should I run?" Again, no runner wants to be injured or sick, so the increase of mileage should be realistic in order to avoid injuries and sicknesses. One very important factor to how often you run is your rest time. Your muscles need time to repair themselves. Many runners will not run more than three days without a rest day. It is true that the stronger the muscles get, the faster they can recover, but especially in the beginning years of training your muscles, it is imperative that you give them adequate rest by taking regular days off for rest.
(Example: You might decide to run on Monday and Tuesday and take Wednesday off. Then you may run Thursday, Friday, and Saturday and take Sunday off).