MISTAKE #1: Opting for the Contractor with the Lowest Bid
Do your due diligence before hiring a contractor. Interview at least two, and ask them for references, ideally from a recent client.
Some contractors will provide a low bid simply to win the job, but then often end up ordering lower quality products or invoicing you with a bunch of change orders throughout the project.
*Note: that's not to say there won't be unexpected additional expenses, even with the most experienced of contractors...that is actually normal and many contractors say you should factor in a cushion of 15% of the total project cost.
Your project proposal should include a detailed description, breakdown of each phase of the project with material and labor costs, as well as a breakdown of the investment disbursement.
Be wary of contractors who give you a "ballpark" figure that is much lower than other prices you've been quoted. If it seems too good to be true, it probably is.
Finally, make sure you're hiring someone who offers a solid warranty. (Ask us about our Bordeaux 10/2/2 Warranty!)