In general, most fitness experts suggest that a person get 10,000 steps in each day for over all good health. 10,000 steps is approximately 5 miles. I know that may seem like a lot, but that just shows us how inactive and sedentary many Americans have become.
What's a good pedometer ? there are tons out there. Check Amazon for OMRON. that's a pedometer brand that is reasonably priced.
Do you have an ipod, iphone or some other smart phone ? There are free pedometer apps you can use on your phone or ipod. I use the NIKE+. it's a free APP. the steps seems pretty accurate although the distance seems off to me.
Remember, this isn't an exact science. A lot of this is a best guestimate.