Hold a tender - send your offer to several companies at once.
Do not choose an offer that will be much cheaper than others.
Purchase a detailed estimate from an organization that is not interested in fraud. Construction of houses, projects and prices for which were prepared, for example, by the same project organization, will be much more efficient. The cost of such an estimate will be about 1% of the cost of the house.
To entrust the construction of a house to companies that value their reputation.
When signing the contract, make sure that after the completion of the work you will receive a warranty card for the completed work.
Do not give a deposit for the construction of the entire house. Reliable construction companies will usually charge you a subscription only for the future stage of work, for example, foundation or roofing work. You will need to pay the other part when signing the act of completed works.
All payments must be made by the construction organization in a documented and correct manner.