Learn the Source of the Documents
Similar writing should be compared with the questioned documents. This means that cursive writing is compared with cursive writing while printing is compared with printing. The same is true for all types of writing.
Signatures on legal forms are best for comparing a signature on a legal form. When comparing the signature on a contract or a deed, find signatures on other deeds, contracts, checks, driver’s licenses or other legal documents. For signatures on a personal letter or greeting card, try to find other signatures that were written on informal documents.
Known (Example) Documents must be authenticated. The reason is that the examiner needs to know that the writing or document against which the questioned documents are being compared are valid. This may require some research by the person who provides the questioned documents and the example documents to the document examiner.