Please take a look at the instructions in USCIS website. If you feel you still need assistance, have an attorney review the documents before submitting. The evidence needed in each circumstance may be different, but the more the better.
Dhenu Savla, Esq.
This answer does not create an attorney-client relationship and is not meant to be relied upon as legal advice.
There is no specific list of documents, but rather, whether the case as whole is evidence of a bona fide marital relationship. Enlist the assistance of a qualified attorney to take you through this in detail, so that you get it right. Best of luck.
Former USCIS and Department of State Embassy Officer -- Khurgel Immigration Law Firm -- 4199 Campus Drive, Suite 550 Irvine, CA 92612. Email: email@example.com Office: (949) 509-6515 Direct: (949) 535-6331 Fax: (949) 509-6599. Kindly note that this blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Remember, this site is simply an internet blog. Do not rely on information here to make important decisions in your life. Make an appointment to meet with a licensed attorney in his or her office (or via Skype or phone) to obtain competent personal and professional guidance.
Letters from third parties such as mother in law, friends or relatives of your USC's spouse, who can vouch to your life together as a married couple. Letters from other married couples with whom you spend time together will also be helpful.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.