Gear designers make efforts to ensure the gear product will survive failure and fulfil the durability and other design requirements. The current article studies different gear design considerations, discusses how to select a microgeometry design accordingly, and investigates the effect of changing the design on the resulting fatigue life. The presented study provides engineers researchers with a good understanding of the different practical design considerations and limitations. The considerations of dependency, tooth microgeometry asymmetry, peak-peak transmission error (PPTE), and misalignment variation are studied and discussed. PPTE is an important factor to study, which acts as an excitation source for Noise, Vibration, and Harshness (NVH). MASTA software tool is used for modelling the gear system and obtaining the misalignment values at different load levels. LDP software tool is used for performing the required gear design calculations and obtaining the generated stresses and PPTE. The macro- and microgeometry designs are discussed, calculations of different cases are performed, and comparisons are presented. The article concludes with a brief discussion that emphasizes the use of the studied considerations and explains under what circumstances should these considerations be adopted to meet the design requirements. The design requirements can conflict with each other, and then a compromised microgeometry design should be obtained. Changing the microgeometry design can significantly affect the predicted fatigue life and damage.