DON'T make a major purchase. This will change your credit score and possibly disqualify you from a mortgage. DON'T change jobs unless it's absolutely necessary. A consistent work history is crucial to lenders.
DON'T give deposit money directly to a For Sale by Owner seller.
DON'T ignore lender requirements. Be absolutely clear on what the lender requires and take care of it.
DON'T go it alone. A reliable real estate professional will help you with all the details including the ones you didn't think of.
DON'T forget to switch utilities. Call the utility companies as soon as you have a contract.