Many thousands of persons hold themselves out to the public as appraisers but few are actually properly trained to do the job. The IRS and knowledgable insurance companies, bank asset managers, and attorneys have been requiring all appraisers they hire to adhere to USPAP as well as Appraisal Foundation standards when selecting appraisers. Members of the general public should as well.
For a good discussion of what it takes to be a qualified appraiser, see this article PERSONAL PROPERTY APPRAISER QUALIFICATION CRITERIA
Although the new standards described in the article above will not go into effect until January 1, 2018, you should be mindful of them now. You can download the Appraisal Foundation brouchure on these new criteria HERE