Looking to Make Some Gains? I'll assume you've been hitting the gym for a few months, seen some positive results. But now it's time to level up and increase your workload and directly increase your strength and muscle size.
First Rule of Muscle Hypertrophy? Know your goals.
The simplest way to define Muscle Hypertrophy is the enlargement of muscle fibers to grow in size. To further break it down, it's to put on mass.
If you've been going to the gym and have participated in weight training, the likelihood is you're looking to accomplish one of these three things:
1. Build Muscle
2. Increase Strength
3. Get Lean
All three of these goals are intertwined. But this brings us to the Second Rule of Hypertrophy, which is extremely important and will directly impact your training and how quickly you'll accomplish your goals: Genetics play a huge role in how your body will adapt because one size does not fit all.
Take two people with the same exact workout routine, they won't develop identical body types, and they won't put on muscle the same way either. So if you're looking for bulky, or lean or toned muscle, take a look at your parents first and see if genetics is on your side. 
To begin the journey to muscle "gains," the body needs to be building, and there needs to be a surplus in calorie intake. This is where genetics plays a significant role. How your body uses the nutrients during training can lead to increased muscle mass or increased fat. It's vital to know, that if you're an average guy looking to add some size, you'll probably end up adding just a little extra fat as well.
Going back to the first rule of Hypertrophy, as you begin to structure your workout plan, you need to be aware of what you're looking to accomplish. Those who are seeking to make "gains" like a bodybuilder need to train and fuel differently than those who are trying to build strength and mass like a powerlifter.
Muscle-growth is a science, and there is a lot of background moving forward with it. And it's always developing and improving. But for the sake of this article, we'll focus on the fundamental components of how to stimulate muscle hypertrophy.
Nutrition in Hypertrophy Training
I'm not going to go into a full blown nutrition guide here, but if you're looking to build muscle, you need to make sure you are in a caloric surplus. You need to get your body into an anabolic state, which is vital for growth. If you're in a caloric deficit, also known as the catabolic state, that's ideal for fat burn. So to possibly answer the next follow up question, building muscle and burning fat are two different things.
Got that out of the way. Perfect.
Diet recommendations for hypertrophy has to do in large part to energy balance and the timing of proteins.
 Protein amounts and the type of proteins impact overall muscular growth and recovery process. How many grams of protein to be taken per pound. I've heard different recommendations, but my favorite and easiest one to follow is if you want to build muscle, say 15 pounds of muscle, look to consume 15 extra grams of protein per pound. So you weight 200 pounds and want to put on 15 pounds of muscle, begin your protein surplus to 215g of protein a day.
Depending on the type of workout you are engaged in, your current weight, basal metabolic rate, all these factors will determine what kind of nutrition plan you should consider.
So why begin adding more calories to your diet to achieve more muscle mass? Your body needs more calories to repair fibers, synthesize new tissue and support recovery.
How to Trigger Hypertrophy?
For a long time, size of muscle seemed to determine people's initial judgements on overall strength of an individual. However, there are times when you've gone to the gym, and the incredibly toned and cut guy is benching 175 pounds, and the pudgy heavier set fella next to him is putting up 275 pounds.
Muscle size does not determine the overall strength, but muscle is muscle, and to achieve muscle growth there first needs to be muscle damage. The best way to achieve muscle growth there needs to be a steady progression of volume and intensity, and this can be attributed to a workout style called progressive overload.
Progressive overload will help the body achieve cellular adaptation to muscle growth. So as your body adapts to the exercises and weight over time, and you increase the weight at the rate of which your body adjusts, you'll build strength and muscle.
Achieving muscle failure can also assist in stimulating protein synthesis for muscle hypertrophy. Various bodybuilders and powerlifters encourage low rep/high weight for muscle failure, but in a recent study, it appears if you take 30-80% of your 1RM and work until failure for three sets, it will trigger and stimulate hypertrophy.  But be mindful that there needs to 1-3 minutes of rest time in between each set. Why? Recruits more maximal amount muscle fibers with each rep.
But most weightlifters don't want to do light weights with high reps until failure. A sound proof way to stimulate muscular hypertrophy is by creating tension with 75-85% of 1RM for 3-5 sets, with 6-8 reps per set. Focusing on primary and secondary muscle groups can promote fatigue and muscle failure as well. A prime example of this is bench press for heavier weights of 6-8 reps followed by moderate weight of incline dumbbell chest flies for 8-15 reps.
Take Aways from Stimulating Muscle Hypertrophy:
As you begin to look into ways to promote muscle growth, your workout plan needs to involve greater activation of muscle fibers to allow for protein synthesis and muscle repair. Begin to consider your goals and create a program that will help you achieve increased muscle mass, or perhaps increased strength. But remember if you want to build muscle it's imperative to get stronger, but how you fuel your body will play a pivotal role in your hypertrophy training plan as well. Muscle growth is a long process, and your body will adapt to increased workloads, but it won't be every week. Make sure to focus on form, and the ability to perform the exercise correctly, because the more muscle fibers recruited per exercise, the stronger and bigger your muscles will become.