We built and moved into our house a year ago. Lessons learned:
- PRICE IT OUT FIRST. Depending on location and market, it's sometimes significanly cheaper to buy than to build.
- Work with a contractor who has a good reputation and a small ego. Basically, if you want something done a certain way, you want someone who is a good craftsman and will give his opinion of what will be cheapest/most solid/most resistant, but YOU'RE the one who is going to live in your house, so you want someone who will do a good job on what YOU want without considering what THEY want. There are two congractors with great reputations near where we are. We chose the one with good email communication, easygoing, straightfoward, and no ego to speak of - he wants to do a good job and be satisfied with his work, basically. A neighbor dealt with his competitor, and is STILL arguing about how they want the finishing details. Someone easy and pleasant to work with totally counts.
- Assume you'll go over budget by 15-20%. For us, I'd planned it, so it was ok, but... about 5% was choices ("oh, we should put the nicer stairs into the basement now", or "we do actually want to wire ceiling lights into the basement ceiling, yes" - things that are cheaper when you build, so worth doing but not on the original estimate) and the other 10% was necessary and unpredictable ("Oh, look, we need significantly more drainage to make sure that we avoid foundation issues. 10K, you say?" and the like - things you really can't avoid or not spend without significant long-term consequences.) Make sure you have the financial leeway.
- Discuss ahead of time what you might want to do yourselves to save money. For example, we sawed the wood and are finishing up the deck-building right now (yeah, took a while) - saved 11K. We assembled an Ikea kitchen ourselves instead of buying materials+installation from the local stores - almost 12K savings. All of these things take a LOT of time and effort... but wind up saving almost 800$/day we put into it, which, IMO, is worth it for the bottom line. Adjust based on your interests and skills, obv, and discuss with your contractor so that the estimates are lowered as needed to account for your work.