The choice of the contractor is one of the most critical stages in the entire construction process, so do not rush and call on the first ad. First, clearly formulate what you expect from employees, what goals you set for them, what means do you have. After that, you must hear no less clear answers from the contractor. Consider and write in advance in the contract the terms of work, and better, material compensation for disruption of the deadlines due to the fault of one of the parties. For specialized work, it is still better to involve specialized companies in order to get professional solutions in a short time. Otherwise, a situation may arise in which your contractor concludes a subcontracting agreement, winding up a profit. If there is a turnkey global work, then it is worth trusting a large company with good ties. But even at trusted firms, demand to show you documents for SRO to protect yourself.