100% Recommend "The Book on Estimating Rehab Costs" by J Scott.... Easily the best book I've seen on the topic. Follow the advice in that book and you'll sound like a pro and won't get taken advantage of. J is an expert and is super methodical. Their book on "Negotiating Real Estate" also has some great tips on getting contractors down. Get tons of bids, break everything down to line items and negotiate the best price for each. Make sure EVERYTHING is in writing, quality of materials, payment schedules, late penalties, etc. Only work with contractors that have great referrals and samples of work. If they say they did a certain project, you can get with the county recorder and see permits pulled and make sure they are in the contractors name. Even talk to the client and ask about the time of completion and the quality. Only give the contractor enough money to complete the next phase of work so you are never in a situation where they bail with your money and have to start over with a new contractor (I've seen it happen more than once). I know that's a lot to digest and it may cost you a little up front, but it will save you tons on the back end, and hopefully establish a great relationship with a contractor you can continue to use. Best of luck!!