Diffusion-weighted magnetic resonance imaging and spectroscopy commonly apply a spin-echo or stimulated echo preparation including sensitizing field gradients. The article reports on a systematic numerical approach to an optimum diffusion preparation considering undesired signal losses caused by relaxation. A large range of possible applications on whole-body units and animal scanners is covered. Instructions for an optimized type and timing of the diffusion preparation are provided for the readership, based on the desired diffusion weighting (b-value), the available maximum field gradient amplitudes, the RF pulse durations and gradient ramp times, and the relaxation characteristics of the specimen (or tissue) of interest. In addition, a new type of diffusion preparation named SEASON (simultaneous Spin-Echo And Stimulated echO preparatioN) is introduced and compared with spin-echo and stimulated echo diffusion preparation. It is demonstrated that spin-echo preparation is superior to stimulated echo preparation in all cases with T 2 :T 1 and in all cases with relatively low diffusion weighting resulting in short duration of diffusion sensitizing gradients l T 2 . For tissues with T 2 T 1 (as musculature or red bone marrow) stimulated echo preparation becomes superior to spin-echo preparation for high ratios b/A 2 (b-value indicates diffusion weighting, A is the maximum gradient amplitude). The new SEASON technique allows a higher yield in signal intensity compared to spin-echo or stimulated echo preparations in clinically relevant cases.