Half marathons are a very popular choice of distance for many runners. They feel pretty special, running 13.1 miles is more than many people can do, but they don't take the same comittment as full marathons. There are many events around the country, one of my favourites being The Shell Four villages half marathon in Helsby. It is a very picturesque route around the local villages (hence the name). It gets booked up very early and takes place in January, well worth a trip out to burn off your Christmas indulgences. This post gives some advice on how to train for a half marathon in such a way that you can get the best out of yourself without injury.
To get the most out of your training it is best to include a variety of training sessions, each of which train your body in a specific way. This post has a summary of the different sessions and how you can include them effectively in your training. Training plans can be found online or you can make your own up using a mix of the sessions here. One thing to remember if you are devising your own plan is not to have two hard sessions together, always seperate them with a rest day or a day of easy running or cross training. The sessions you include in your plan depend on your fitness, the race you are training for (if any), the amount of time available to train and the length of time you have been running.