Ideally, you’ll be doing five to 12 repetitions, but your focus should be on your form rather than repetition or weights, because if you do the exercise wrong you could experience back pain or even injury. After you’ve sorted your form out, you can discover what number of repetitions works for you. Remember to do three or four sets of each shoulder exercise, and keep your rest time between each set and exercise at 90-120 seconds. You need to do two types of compound exercises before you move on to your isolation exercises, so that your entire deltoid gets warmed up and your muscles are stimulated fully.
After this, you should target every part of your shoulder muscles by doing some side shoulder raises and front shoulder raises. Again, remember your form, and use a mirror to make sure you’re doing it properly as it is harder to keep the form right when the weight is further from your body. Do standing shoulder raises with a straight back, not leaning into the weight itself, because the weights should only be moved by your shoulders, not by jerking or swinging the weights up. If this happens, try using lighter weights.
Finally, make sure your workout is less than 45 minutes long, and eat something roughly an hour before you start. This ensures muscle growth because it stores glycogen in your muscles, which your body then uses. After exercising, eat a meal of three parts carbohydrates and one part protein because your muscles are at their most susceptible to nutrients at this point. Last but not least, sleep is the most important part of your exercise regime. If you don’t get 7-9 hours of restful sleep, you won’t get the weight gain results you’re after.