The key to improving anything is consistency, and sheer determination that you will meet and exceed your goals.
Like
@Kangarooj said, don’t run consecutively so take a rest from running the day after running. But remember, the amount of running you do will reflect on how quickly you meet your goal time.
As an example, I know a guy who got his 1.5 mile down from 12:33 to 9:17 over a two year period whilst we were at college. His method? Going to college every Saturday morning and running the route twice, so one 3 mile run a week. As well as other CV training such as cycling, rowing and swimming in the week.
Oh, and he was out for 2 months from injury