Invest the time, do the due diligence and definitely speak to people who have worked with your prospective contractor or subs in the past. Again, spend the time on this... there is no better use of your time (yes, I'm talking from experience and have paid the dumb tax of not doing this enough!). If I look at the projects in the past that have not gone well, 90% of the time it was been related to the contractor or subs… whether it was not showing up, taking twice as long, doing shotty work, changing the scope and/or costs/change orders... it all adds up.