Choosing the right contractor is one of the best advice I can give you. The lower bidder doesn't necessarily is the best choice of a contractor. Normally, the lower bidders, it might be good on a paper, but you're gonna end up with low quality work, low quality product. A lot of change ordered during the construction process.
Should look into the value, the transparency, and references and outcome of a previous project before you're deciding on your contractor. So that is very important. The other thing is when you're choosing a contractor make sure references are checked out, all the plans and building. He build, have references of pictures, images, or anything that he can validate your contractor.