A registered lease agreement/ leave and license should be done. That safeguards the interests of the landlord and the tenant too. It is to be registered before the registrar office. It contains all the terms and conditions of the agreement and witnesses attest to it.
A lawyer should be engaged who will draft an agreement specific to you not just a general agreement.
Force majuere has always been there. It is now that the people have come to realise its importance. It means that forces beyond the control of either kf the party the agreement would not hold good/ cannot be enforced.