If you have a favorite loop that you run often, make sure there are some hills in there. Also try throwing in some hill repeats. Hill work is hard, but will make you stronger and faster on race day. Put in the miles. There's no substitute for putting in the miles.
Miles are essentially a synonym for hard work.
This hard work acts as the foundation on which all of your running goals will be built and achieved. I used to run about 20 miles a day or about 150 miles per week during peak training periods. You should determine your goals and adjust your mileage accordingly. Have clear goals and keep them to yourself. I found that talking about my goals never helped me achieve any of them.