I have gone through this process 2 times for my parents and for my in-laws, thought this might be useful for some more people like you.
Here is the list of documents you need to prepare before appearing for the VISA interview. You need to prepare the below "From the visitor" documents for blocking an interview date. "From the Sponsor" documents needs to be ready before going for the interview. Suggestion is, Start collecting the documents well in advance since few documents like bank statement takes time .
From the visitor
2. photograph - 50x50 cm with plain background (almost all photo studios knows the specifications of a photo for US Consulate)
http://chennai.usconsulate.gov/howtoapply.html - this is the official website of US Consulate, Chennai
3. DS-160 Online application - If you are the sponsor, you can fill it online, by just getting your parents ( or in-laws) passport details - print the confirmation page at the end.
4. VISA fee receipt from the HDFC bank ( amount is specified by the consulate, so before taking the receipt, check US Consulate webpage)
5. Use VFS to block the appointment date with the Consulate - HDFC receipt and barcode is mandatory
6. Take the print out of the appointment letter
From the sponsor
1. Form I-134 'Affidavit of Support form' - it is recommended that you give one form for each visitor, though it is your father and mother
2. Sponsor letter / Letter to the consulate - addressing the US Consulate that during the stay, I will bear all the expenses for the visitors
3. Invitation letter - Addressing the visitor to come and visit the USA
4. Pay slips of last 3 months
5. Last 6 months bank statement - online statement would do
6. Bank account verification letter - this is to ensure that sponsor has enough to support the expenses of the visitor - note, few banks takes time to give this.
7. Employment letter - it usually gives details about nature of job, salary and permanent or contract
8. W2 statements of prev years
9. Relationship statement - your birth certificate, if the visitors are your parents, or your spouses birth certificate if the visitors are your in-laws. In case if it is for your in-laws, entire passport of your spouse and your marriage certificate is necessary.
10. photocopy of your passport for all pages
11. Legal visa papers like H1/L1 document, or EAD/ green card
Recommended documents from the visitor
Below are just to make the consulate officer confident that the visitor will come back to India after their short stay in United States.
1. Property documents like a house or agriculture land papers
2. Bank statement showing the monthly income / pension
3. Business statements
4. Any proof like a ration card if they are taking care of their parents
1. If parents can not talk english fluently, adwise them to take the interview in regional language, that makes the parents not to be tensed also avoids unnecessary miscommunications
2. Better you do for both parents together
Usually if you are sponsoring for your parents or in-laws, mostly there should not be any issues unless they have any legal / crime issues.
1. Your passport and interview letters verified at gate
2. your documents are verified and tumb impressions taken
3. giving your HDFC receipt at the counter
4. taking the interview - if your VISA approved, they take the passport and send in courier
Along with all these, good luck helps more..:-)
Thanks for reading, hope you get your visitors soon here...