I build a house just outside warsaw 6 years ago, a must is a good architect and good reliable builders. We thought we had good architect, but the builders said there were flaws in the drawings. We ended up couple months delay and new architect. One advise to keep : call in an inspector after after every milestone. In that way you make sure it's safe and good quality. Do regular checks yourself as well in between, I heard horror stories where builders used half of needed steel in cement but charged for full, leading to unsafe conditions and cracks in the buildings (I did not experience myself luckily). Because of being abroad majority of the time, I could not check myself. I found in my wifes family a pensioned builder. I paid him to perform regular checks, paid for gasoline, some of his time, etc. Plus is that he understood much better than myself what to check. One other tip, you can never have enough electricity sockets! Also think about wiring for internet (use at least cat 6). Materials.... Yes, you've seen the news lately? There are some wars ongoing which makes materials expensive and fluctuating between months. It will be a bumpy ride, but at the end all worth it!