Muscle growth aka muscular hypertrophy is when protein synthesis exceeds protein breakdown resulting in increased size and mass of the muscles. 

For hypertrophy, the goal of exercises is to isolate muscles and create as much micro-tears to it for growth, as well as maximize mechanical tension. Generally, the optimal rep range for hypertrophy is 8-12 with maximum resistance. Reping the exercise should also be controlled, focused on isolating the muscle. There should be a full stretch of the muscle and full contraction in each rep for a full range of motion(ROM). On the eccentric(going along the force of resistance), the movement should be slow and controlled, about 1-2 seconds on the way down. At the bottom of the movement, there should be a slight slight pause. This is due to the muscles and tendons naturally having a stretch reflex that uses momentum to 'bounce up' against the resistance. Without the slight pause, the tension will be lesser on the muscles, losing focus on isolating the muscles, and injury might result if the load is too much. On the concentric, the movement should be fast and explosive, but controlled such that the form stays the same, really getting the 'squeeze' in the muscle. Rest between sets should be 2-5min.

At every training, intensity should be dialed to the max, meaning that you push yourself to failure at every set. With that, you will grow bigger and stronger, and will need a bigger stimulus for your muscles to grow in the next training session. Some ways to increase the stimulus include increasing the resistance, reps, and sets, or doing drop sets where you go beyond failure. After the last rep is done, and the next is failed in a set, the resistance is lowered to pump out more reps until failiure.

Mechanical tension means the contractile force of a muscle opposing a resistance. This force is the main driver for muscle growth, so we want to maximise it. How you may ask. To maximize mechanical tension, we have to push an exercise to failure. As the reps in the set approaches failure, the speed of the concentric naturally decreases even if we push as hard as we can. You can try it out yourself. Do as many push ups as you can and you'll realize the last few reps are often the hardest and slowest. These last few reps are actually the reps where mechanical tension is maximized, following the force-velocity relationship. So to achieve maximum mechanical tension, take your sets to absolute failure, and even then, try to push out another rep until your muscles give ou

The force-velocity relationship relates the speed at which a muslce changes length with the force of this contraction and resultant power output(force x velocity = power). As reps approach failure, power, which is the amount of energy transferred per unit time, increases. But due to muscle fatigue and a variety of other reasons like endurance or pain threshold, the velocity at which the muscle is contracted, or the rep is performed, is slower. Hence the amount of force has to be higher to match the power output.

Ego lifting is a term for lifting heavier than you can for the sake of comforting your ego. It may stem from peer pressure to show off, or comparison, or just for fun. Ego lifting can lead to loss of gains, as reps are not performed to the highest quality, resulting in other muscle groups being used instead of isolating the singular muscle group for growth in an exercise. It could also lead to injury like muscle tears, as the load on the muscles may be too much for the tendons or muscles to handle due to lack of training. Avoid this by training practically, really knowing what your goals are and being cautious of injury.

Intensity is the difficulty of the exercise. To up the intensity is to up the load and how close you push your reps to failure. If you do not push to failure and train just to get that specific amount of reps, you won't achieve mechanical tension, and will be losing out on gains. If you can go for a higher difficulty, go for it. Don't short change yourself. Don't be afraid of the pain. Push through it. 

Dynamic warming up brings circulation to muscles, joints, tendons and ligaments, preventing injuries. Not warming up can lead to injuries, as well as stiff movements.