To cut costs, some people might want to go with the cheapest bid but you should never do that. It's best to be right in the middle because the cheapest contractor might have missed something that they'll add back into the price later on, or they might not produce the caliber of work that you'd expect.

None of this is really that hard. You are making all these decisions anyway. Usually you just hire someone to coordinate them for you.

Never take [subcontractors] on their word. Get a good, full contract and make sure they are licensed and insured. Always verify their references. That's very important.