Step One: Have clear and open motives for designing a new home. Make sure it is not a whim or notion to impress anyone other than yourself. Make sure it is something that is on your lifetime "to do" list. Don't do it because everyone else is doing it, don't do it because you are bored, don't do it to please a parent and most of all, don't do it to save a marriage. Designing a home for yourself should be a reflection of who you are and how you want to live in this world. Be real with this first and the home you live in will fall into place.
The most disheartening thing I run across in home design is the couple who "desperately" want a new house. The home they are currently living in is structurally sound, seems to be large enough to fit their family, is in a decent neighborhood and from all outward appearances, is a pretty good family home. Their list of complaints about the existing house are vague, inconsistant and differ greatly from him to her. These are the first warning signs I get that all in not right in this house and most of the problems are probably coming from the bedroom. Another warning sign is that one person is much more involved in the design process than the other and the uninterested one refuses to give any constructive input. These situations need a marriage counselor not a residential designer. It's very sad when you spend the time to design a nice home for a couple and they file for divorce before the roof is on it. A new home won't solve all your problems, if your spouse claims they need their own space, make sure you know what they mean. They might not be talking about just another room in the house.
Step two: Have realistic expectations about what you can and cannot afford. Visit open houses, parades of homes or local home shows to get a feel for what things cost in your area. Research the cost of home loans, insurace and local property taxes, familiarize yourself with the location, size and costs of lots, these are all expenses that contribute to the price of the home. Check your credit scores, they need to be at their best right now-before you talk to anyone at the bank. Go on-line and find a banking site that offers a loan calculator. Plug in the numbers that you think will work for you, calculating principle borrowed, interest rate, length of loan and monthly payment. Figure at least 10% down and don't forget to add the cost of taxes and insurance to the monthly payment number. Play with this until you are comfortable with the numbers. If you and your spouse have major disagreements about these numbers, go back to step one and re-think your motives and goals.
I usually suggest to my clients that they make a wish list of all the things they want in their new home and to be as specific as possible. If you want pink ceramic tile floors in all the bathrooms, write it down. If you want clean, angular lines throughout the home, write it down. If you want a second floor balcony or knotty pine trim or in-floor heat, write it down. Now is the time to brain storm all the possibilities. Consider all the wishes of everyone who lives in the house, sometimes the kids have the best ideas. Now, being rather ruthless, highlight, star, underline or otherwise mark all the items on the list that are needed. Is pink ceramic tile in all the baths really needed? Is the garbage disposal really needed? How about the $5,000 kitchen range? Be honest and make sure everyone has a say about the items that are truely needed. The person who takes out the garbage every day might rate the recycling center higher than the pink ceramic tile and the one who cleans the bathrooms might rate the ceramic tile higher than the color pink. However you do it, everything on the list will be divided into wants and needs and then they will be ranked most inportant to least important. When the discussion comes down to money, you might eliminate most of the want list and some of the bottom things on the need list. Be open and honest with what you really need and if it looks like there is the possibility of upgrading things in the future, items like flooring, appliances, light fixtures, furnishings and counter tops can be replaced when that lottery ticket wins the big one for you.