Include as Much Documentation as Possible When Filing the Petition
Failure to provide the necessary evidence/documents can result in significant delay of your petition/application, and can ultimately lead to its denial. If you failed to provide the necessary evidence/documents, upon your initial filing, generally, you will "Request for Evidence" (or RFE) will be sent to you. The RFE will often not allow you a whole lot of time to gather the necessary evidence/documents. If you do not provide the necessary evidence/documents pursuant to the RFE, your petition or application will almost certainly be denied. To make sure that your petition or application is approved timely, it is important that you submit the right evidence/documents when you initially file your petition or application.
READ THE INSTRUCTIONS on the petition or application.
The types of evidence/documents that you need to submit depends on the type of petition or application you are filing (for example, if you are filing for a fiance'/j visa, and you and/or fiance has been previously married, you will need to submit divorce decrees to prove that you and your fiance are both currently single). The instructions will tell you the types of documents that you need to submit. If you do not have the instructions for a particular form, go to link .
When submitting documents, it is always a good idea to submit certified copies (ie documents containing original official governmental seals, stamps, signatures, etc.) If you are submitting an original document, one for which you would like back, a form G-588 "Request for Return of Original Documents" should also be submitted.
Foreign Language Documents
If you are submitting evidence/documents which are in a language other than English, make sure that you have them translated. The translated documents should be accompanied by a certification from the translator that the translation is accurate.
Make a Copy for Yourself
Finally, make sure you make a copy of everything you submit for yourself. This will help you determine later what was actually submitted, if it becomes an issue.