Here's more for your list..
1. If you are having to do the I-751 in two years (ROC), START COLLECTING DATA NOW! Get a plastic bin, or old shoe box, or something, and drop any mail addressed to both of you (holiday greetings, invitations, personal notes, etc.) in it. Have copies of all rental leases/deeds/mortgages in the box (or scan them electronically). Do the same with an electronic folder on one of your laptops or desktops or have a USB stick that lives in the shoebox, too. Diligently copy any and all bank statements, insurance papers with both names, credit card statements, yearly tax transcripts to your hard drive/thumb drive. If you don't keep things electronically, then save the paper copies. Do this throughout the two years between immigration and ROC, and save yourself the heartache of trying to find back copies of everything at the last minute.
2. Have both parties listed on rental/homeowners/car insurance policies as an authorized claimant. This has nothing to do with USCIS and everything to do with protecting each other in a terrible situation. Example: your house is demolished in a storm, and the person who is listed on the policy dies. The other spouse cannot file an insurance claim if they are not listed as a party that is AUTHORIZED to file a claim.
3. Make wills and have medical powers of attorney for each of you. USCIS likes to see this, as it shows that both parties are looking to the future.
4. If you travel, take pictures together with recognizable landmarks in the background. Keep all boarding passes of airline/train trips. If you make a hotel reservation, put BOTH names on the reservation. Save your receipts and copies of the reservations. If you visit family or friends, take pictures together.
5. If you don't have kids, then pets can count! Have both names on your account at the vet, and print out vet receipts. We shipped our cat from Australia to the US and used all the paperwork from HER travel as documentation.
Best of luck on the rest of your journey!!!
Sukie in NY