One of the most direct ways to find a grave, if the cemetery has a business office, is to go and talk with the staff. Alternatively, contacting the local city hall can help to locate graves in nearby cemeteries.
Some rural town might not have a business office at smaller cemeteries. If this is the case, the person looking for the grave should go to city hall. It should have records of every death certificate and which cemetery the person was buried at. If city hall is no help you can also go to a local courthouse or library and receive the same information. A good online tool can be found at www.findgrave.com, if you have access to a computer.
If the person you are searching for was cremated, it may be more difficult to locate the memorial. Not all cemeteries offer graves for cremation remains, and there may be no formal record of a non-grave memorial stone. You can always go to the cemetery and search for the marker if you know which facility was used. Several cemeteries have road names and maps to help interested parties to search manually. Going row by row by foot is always an option, too, though this can be very time-consuming.