You have a few options when it comes to setting your budget. Your first option is to give your designer a dollar amount early on. In this case, it is incumbent upon the designer you are working with to know his or her abilities and limits, Bruce says. "I love architects and designers, but some of them are better than others at designing to a number," he says. "The worst and most painful of the many things that can go wrong is to see your dream start to come together on paper, fall in love with this imagined space and then the number comes back from the builder and it's so off that there's just crushed dreams and hatred all over the place."

The other option is to stay open with your budget. "Give a rough ballpark, test it in the real world and be ready to either scale it back or throw more money on the pile," Bruce says.