With all my offers I send out for my buyers, I always include :
Copy of DU Findings (This a system run by Fannie Mae, saying they will buy the loan)
Copy of Credit Report
Copy of Proof of Funds ( to include down payment & closing cost)
Access to my buyers lender for the agent to call and check status of the loan
The bottom line is to convince you ( the seller) that the buyer is 100% capable of purchasing your home.
P.S. I'm in Fairfield too, let me know if I can help you.
Broker / Owner