As others have posted you need to have a complete water analysis done. In most communities there a companies that install and maintain water conditioning equipment and they typically offer testing services as part of there install business. If you have a significant problem you may want to pay for these services.
If you want to do it yourself--find a water testing laboratory. The Board of Health may be able to give you a list of labs in your area.
Once you have your water analysis there are on line companies that sell equipment and will recommend appropriate equipment based on your water analysis.
Here is one that I have had some satisfactory dealings with:http://www.ohiopurewaterco.com/shop/customer/home.php
If you end up with a softener as the solution, or part of the solution I highly recommend a two tank system. Two tank systems are more expensive but, in my experience, they are worth it. I have a Fleck 9000 series two tank system and have been very pleased with it. It has been isntalled for 7 years.