It seems obvious, but it’s good to note that the first step to buying a house is making the decision to buy. Consider the reasons you want a new house and write them down. Determine how long you want to live in the new house does buying still make good financial sense? Can you afford a house that will meet your list of requirements? A good rule of thumb is your mortgage payment should not exceed 1/3 – 1/2 of your net monthly income.