The key factors include load distribution, vibration isolation, thermal expansion accommodation, and alignment precision. The design must ensure that the engine weight is evenly distributed to prevent stress concentration. Vibration isolation is crucial to minimize the transfer of engine vibrations to the vehicle chassis, improving comfort and reducing noise. Accommodation for thermal expansion prevents mount failure due to temperature variations during operation. Lastly, precise alignment is necessary to maintain driveline geometry and prevent undue wear on connected components.