The first and most important key for muscle growth is, “mechanical loading.” This is just a fancy way to say, “Resistance training.” You cannot make significant gains without lifting! Make sure the majority of your training weights are over 60% of your 1RM and shoot for 6-12 reps per set at these higher intensities to maximize hypertrophy. Periodization is also important to continue gains in strength to allow for more mechanical loading! Check out our article, “What Causes Growth?” here for more info.
Reference: Wackerhage, H., Schoenfeld, B. J., Hamilton, D. L., Lehti, M., & Hulmi, J. J. (2018). Stimuli and sensors that initiate skeletal muscle hypertrophy following resistance exercise. Journal of Applied Physiology.