A combination of two optical elements: neutron guide followed by monochromator for neutron reflectometer was optimised. Several shapes of neutron guide were studied: classical, parabolic and elliptic ones. Flat or focusing monochromators considered. Guide coating and monochromator mosaicity were also varied. Calculations were made in the McStas package. The optimal combination for the maximum flux at the sample was found. For better performance an additional neutron guide after the monochromator is proposed.