Shoulders problems are usually the bottleneck in training heavy weights, what kind of exercise or stretches would you do to ensure a healthy shoulder?
Here are some strategies I have found to be useful.
Do not program a separate shoulder day. Prefer push/pull split routines instead. Otherwise your supraspinatus and front deltoids will work twice (during chest day and shoulder day) and so your infraspinatus and rear delts as well (during back day and shoulder day). This reduces their recovery ability and increases the chances for injury.
Prefer shoulder exercises that don't force your humerus to go overhead, i.e. prefer lateral raises with perfect form (see here or here and be sure to do the "Full Can" version, i.e. with thumbs pointing upwards) instead of shoulder presses. The reason being the reduction of the subacromial space during overhead movements. This is usually not a problem if you are young and have perfect form. But sooner or later this is an issue for many bodybuilders.
Avoid behind-the-neck press and behind-the-neck pulldown exercises. There is little advantage and great risk of shoulder injury. Avoid keeping pullups unless you are a pro in great physical shape. Prefer the pulldown to your chest variation, and pullups with slow, controlled tempo. As for shoulder presses please see point 2 but, if you decide to do shoulder presses nevertheless, the neutral grip with elbows pointing forward is anatomically less likely to cause subacromial impingement.
If you are a beginner, don't bench press until you are able to do a set of 20 perfect-form push ups in a row. Push ups work the same muscles and many more, in a more shoulder-friendly way. Only when push ups are too easy for you it is time to start bench pressing. If that is not the case, then forget momentarily about the bench press and start by doing pushups with your hands on elevated surfaces (on top of a bench, on the bar of a Smith machine...) until you are able to do them on the floor.
Add some swimming to your regular training schedule. Yeap, swimming is great for your shoulder joint health. Sustained movement under low stress promotes blood flow into the muscles and nourishes your cartilages. Unluckily, many of us only follow this advice when shoulder problems appear after a lifetime of ignoring it. I am NOT saying "quit lifting" but only "add swimming sessions here and there in your rest days".
Add internal rotations and external rotations with a rubber band AS THE VERY LAST EXERCISES in your workouts (internal rotation during push day, external rotation during pull day). These should be done with very light weights. They help keeping your rotator cuff tendons healthy. Never do them before any other kind of work: you want those tiny muscle fresh and ready to assist you with the big exercises.
Finish your workouts with the infraspinatus stretch and the supraspinatus stretch. Not only they help keeping your shoulder healthy, but also they are useful indicators: If any of those two stretches is painful, then something nasty is probably going on inside your shoulder and it is time to examine carefully what you are doing and how to improve your technique/ change exercises/ introduce additional rest days before it is too late and you find yourself under the surgeon's knife.