1. Check with your Secretary of state.  Check the business you want to hire using the entity name in the corporation search even if it's not a corporation.  Also, search the Registered Agent database using the entity owners name.  Any additional business names that come up you can search the Corporation database.  Watch out for common names.  A PI would know how to confirm ownership of a business if you run into a problem.

2.  Check with the Better Business Bureau.

3.  State court record system.  Some states offer legal public record databases where you can search using someone's name, court document number, etc.  In Missouri you can use Case.Net.

4. Google search names, addresses, and just about anything.  You never know what will show up.

What a Professional Investigator Can Do

1. Everything mentioned above using skills and experience including the use of exclusive resources

2. Criminal Background Check in a timely manner

3. Tax Id Search and verification

What you should do when hiring a contractor

1. Get everything in writing.  Be specific whether you are paying per hour or per job.  If per hour make sure there is an understanding that the job must be done properly.  IE: if you hire someone by the hour to hang a shelf and after they install the shelf it falls the contractor can insist that he be paid based on the time he spent on the project even if the shelf falls.  Then you will have to pay someone to hang it properly.

2. If possible make arrangements to pay upon completion.  NEVER pay a contractor anything before the job has begun.  If they insist do yourself a favor and hire someone else. IE: the contractor wants you to pay for supplies and goes shopping on your behalf and asks for money up front.  He buys the most expensive or cheapest materials for the job OR runs off with your money.  The best way to handle this is to go with the contractor to make the purchase OR allow him to use his own money, which most will do, and ask for a receipt. 

3. Call your friends and ask for a referral.  The safest way to to find a reliable contractor is through someone you know who has experienced the contractors services.  In most cases you will be thankful.