Power to issue directions permits procedural guidelines but forbids directing disposal of a particular case in a specific manner. Section 10 empowers the Central Board of Direct Taxes to issue directions and orders to income-tax authorities, but forbids any direction that would require a designated authority to dispose of a particular case in a particular manner. The Board may issue general or special orders prescribing guidelines, principles or procedures for classes of cases, including revenue collection, and may do so when it considers it necessary in the public interest.