Shoulders is a hard muscle to train. If you don't give it your all nothing will grow.
You can divide the shoulder muscle (M. deltoideus) in three functional parts, the front delt, the side delt and the rear delt. To train your shoulder right you have to stimulate all three parts.
Easiest to train is probably the front delt, since every shoulder press will mainly use the front delt.
So we actually won't focus much on that part. Much more important, especially for shoulder health is the rear deltoid.
But let's begin our shoulder workout:
Exercise 1: Standing Overhead Barbell Press. This one is a classic it works your whole body and is in my opinion the best upper body exercise in existance! You probably need to start with low weight but that's totally fine. Keep a straight back, if needed use a belt. Do the OHP heavy, 3 sets 5 reps.
Exercise 2: Sitting Machine Side Lateral raise. Machine because form is king for this exercise, and the machine enables you to concentrate 100% on the form. Squeeze hard at the top and go real slow to the bottom again. 4 sets 8-12 reps.
Exercise 3: Face Pulls. My favorite exercise. Targets the rear delts and will keep your shoulder heavy. Not much sense talking about when you have a great video to show how it's done.
Exercise 4: Sitting Dumbbell Shoulder Press. Another pressing movement, fairly easy to execute. Use a decently heavy weight. Squeeze on every rep, never lose tension in your shoulders! 4 sets 8-12 reps.
Exercise 5: Seated Bent-Over Rear Delt Fly.
Now if you can still handle it.
Bonus Exercise: Heavy Shrugs. Doesn't matter which variation, dumbbell, barbell, trap-bar or kettlebell. Important is a squeeze and hold for 2 seconds on top and a slow negative.
Try it as a shoulder day!