Normally around 2 or 3 times a week and I do about 3 miles a time, however I have not run since March.
You don;t need much of plan for your first Hm if you aren't particular goal orientated. However, it is useful to have a rough idea about what you should be doing.
I would work on slowly increasing your number of running days to 4 and then 5, but keep at each level or 4 weeks or so. Similarly, just work on increasing the distance of the runs a little. Have some runs a little longer than your average, others shorter. So if you currently do 3 miles, try to make one of them 4 to 5 miles but compensate with another at only 2 miles. over time you want to gently push the long run out, by a mile or so ever 3 weeks, on the 4th week have a cut back so the long run is easy again. Eventually the Long run can meet or exceed the half marathon distance, although its not a problem if your longest run before the race is somewhat short. Most important thing is not to push things too far, too fast.
At this stage your biggest gains come form simply, being out the running and making sure you recover. No real need for any form of intervals or hills which increase injury risk when you are not well trained. It is very surprising but running slowly will let you race much faster, so try to ignore paces or the time it takes to compete your favorite run. Training at a comfortable pace will ensure that pace gradually gets faster and faster without forcing it.
Since you want be running too much (since you are starting at 2-3 times a week 3 miles) you can supplement with cycling, swimming or sports. Swimming can help recovery and increases core strength. Cycling will allow you to raise your heart beat with some hard intervals without adding any joint stress.
Get a proper pair of running shoes fitted,. Keep an eye on injuries, aches pains.
