Before training you need to ask yourself, where am I? What kind of shape am I in? Have I been sitting around, watching TV, or am I able to run a 5K or maybe a 10K without much preparation? How is my weight? Do I need to lose some pounds or am I fine? Knowing where you are and where you need to be is key. No good training program can be designed unless you know those pieces of information. Since everyone is different, there are tons of potential recipes to choose from and chances are none will fit very well.
It is just as easy to design your own program from scratch as it is to try to fit a ready-to-wear recipe that you found in a magazine. Divide your training into two phases: building a base, and adding intensity. It is best not to confuse these periods.
During period one you need to get several things accomplished but getting comfortable with the distance and the duration is the main goal. It is also the time to get your weight corrected if necessary. During the second period you need to focus on intensity and work very hard to get your physiology up a few notches. You also need to leave enough time to recover. For a short race a few days is fine, for endurance events, you may need to taper for two weeks or more.
It is always easier to work backwards from race day. It is also best to stay flexible and be ready to adjust your plan should you progress slower or faster than anticipated. You need to review your plan periodically and see where you are. Are you on track to reach your goals? If not, adjustments may be needed. More about that later.