First of all, I'm just a run for fun type of guy. I like to keep a nice, consistent running schedule of 45-50 mpw. However, every once in a while I will do a race like a 5k to half marathon. I'm even planning on doing a marathon late this spring.
My question is how much tapering should I do and how long before the race should I taper? I may not be a serious racer, but I still want to run well. Also, should the distance of my race affect the taper?
It can take a lot of experimentation to get the taper right. Some research (and this fellow backs it up pretty well with real life results) by Inigo Mujika shows that the proper taper is individual to a great degree.
If you are going to be in Colorado Springs April 7th, Dr. Mujika is speaking at the OTC. There is a fee for the presentation, but it is open to the public.
The whole tapering paradigm is based on the idea that you bump your mileage up to (let us say) 100mpw or more in the last couple of months before a marathon, and then gradually let your body recover in the last three weeks. If you're not going to do more than 45-50mpw, and you've been running that consistently, then you probably don't have to do much of a taper. Just avoid racing the last two weeks, and cut the mileage by half or more.