Some states require that every commercial moving service be licensed through the state Department of Transportation. If this is true of your state, it's recommended that you only use licensed movers, in order to get all the protection that the law provides.
Be sure you understand the extent of your commercial moving service's liability for any losses or damages that occur during the move. To make sure you're covered adequately, declare an exact cash value for each item, or pay extra for full replacement-value protection.