Do pay all your credit cards on time.
Do keep a positive balance in all of your checking and savings accounts.
Do keep your money right where it is. Changing banks or moving money back and forth will require explanation, which is just more paperwork for you and your lender.
Do think about the future. Consider what you want today and for the next 5 years. The average person stays in a home 7-10 years. If you are confident this is a starter home, see if your lender can approve you for a shorter-term (lower interest rate) loan. Or, if this is your forever home, ask for loan options that help you maximize principal verses interest rate payments.
Do relax. You are with the right team. Trust them and give them what they need to get you approved. You control a lot of the timing. If documentation is required, get it to your originator as soon as possible.
Do keep your loan originator’s phone number. They are a great source when you want to ask about refinancing, buying a second home or a new home in the future. They already have your history and they can advise you rather quickly.