You may recruit more muscles than just the group you're focused on. Getting back to dumbbell presses, you not only use the pectorals, anterior deltoid (front of the shoulder) and triceps, but you may need other shoulder and back muscles to coordinate and hold your body steady during the exercises. Likewise, if you're doing standing front raises, you will naturally recruit muscles in your abdomen and back to steady your body.

For Arnold, building a big chest started with training for strength since he competed as a powerlifter early in his career. With a foundation of strength, Arnold discovered that gains in size came easier. Consider an offseason powerlifting cycle to help boost all your numbers before shifting back into bodybuilding-style training. For the record, Arnold once benched 225 pounds for 60 reps!
You can use your own body weight for resistance exercise. Pushups, sit-ups, chin-ups, squat thrusts, lunges, and step-ups are just some of the exercises that you can do to strengthen your body. The advantage of these exercises is that you can do most of them anywhere, and even though you can't change your body weight to increase or decrease the resistance, there are some things you can do to increase the resistance. Here are some suggestions.

When you start resistance training, most of your initial increase in strength is due to a phenomenon called neural adaptation. This means that the nerves servicing the muscles change their behaviour. The nerves are thought to fire more frequently (prompting increased muscle contraction) and more motor units are recruited to perform the contraction (a motor unit is the nerve cell and its associated muscle fibres). This means you become stronger, but the muscles remain the same size – you’ve hit the plateau.
The first way is to do two exercises for the same muscle group at once (like in the Pre-Exhaustion technique). The drawback to this technique is that you will not be as strong as you usually are on the second exercise. The second and best way to superset is by pairing exercises of opposing muscle groups, antagonist groups, such as Chest & Back, Thighs & Hamstrings, Biceps & Triceps, Front Delts & Rear Delts, Upper Abs and Lower Abs. When pairing antagonistic exercises, there is no drop in strength whatsoever. As a matter of fact, sometimes our strength goes up due to the fact that the blood in the opposite muscle group helps you perform the other. For instance, if you superset dumbbell curls with triceps extensions, the blood in the biceps help you to do more weight in the triceps extensions.
One of the most persistent questions floating around the minds of many aspiring bodybuilders is “What is the best way to train to build muscle?”. The answers are as varied as the numerous pieces of gym equipment that occupy any fitness establishment. There are many choices as to the best exercises to use, how many sets and reps, how many days per week to train and what type of program to follow.
If you're using a resistance band, keep in mind that one band might not cut it for your entire body. Different muscles have different strengths, so you may want to buy two different resistance bands in different thickness, which determines how difficult they'll be to use. In general, if you're able to complete 8 reps of an exercise using a band, you'll want to select another that provides a greater amount of resistance. 
Carbohydrates play an important role for bodybuilders. They give the body energy to deal with the rigors of training and recovery. Carbohydrates also promote secretion of insulin, a hormone enabling cells to get the glucose they need. Insulin also carries amino acids into cells and promotes protein synthesis.[26] Insulin has steroid-like effects in terms of muscle gains.[27] It is impossible to promote protein synthesis without the existence of insulin, which means that without ingesting carbohydrates or protein—which also induces the release of insulin—it is impossible to add muscle mass.[28] Bodybuilders seek out low-glycemic polysaccharides and other slowly digesting carbohydrates, which release energy in a more stable fashion than high-glycemic sugars and starches. This is important as high-glycemic carbohydrates cause a sharp insulin response, which places the body in a state where it is likely to store additional food energy as fat. However, bodybuilders frequently do ingest some quickly digesting sugars (often in form of pure dextrose or maltodextrin) just before, during, and/or just after a workout. This may help to replenish glycogen stored within the muscle, and to stimulate muscle protein synthesis.[29]