One of the most important things when you start training is to ask for imformation about which exercises should you be doing and which exercises you shouldnt; but it is not only about getting the information, but from who you are getting that information.
New people that come to the gym, or even old customers at gyms that get impressed with BS, tend to follow people that instead of helping are actually damaging you with their heavy, ego lifting.
You have to be aware that heavy lifting is just for some, and lifting heavy doesn't guarantee you to be big or fit. Powerlifting and bodybuilding are different sports and the goals from one to the other are way apart.
These are some heavy exercises that you shouldn't be doing unless a professional is supervising you in every aspect of it:
You can't jump into a gym or in social media without seeing some dude, that most of the time is not even big, doing some really heavy deadlifts. Do not get impressed by these people. First of all; almost everyone can do heavy deadlifts after a few months of training. Second; the deadlifts do give you strength, but for bodybuilding purposes if gives you a xmas tree shape on the lower back which most of the people don't ever get. And third; the risk of getting a lower back injury is HUGE and you really don't want to have a serious back injury, it will change your life in every aspect.
Leg presses are a great exercise to give your legs a way better shape; the problem is, that most of the people just use it as a ego lift because you can go super heavy on the leg press machine. There is no problem with going heavy, the real problem is that they go heavy, but
they can't move the weight the right way; they just want to show people that they are heavy lifters. If you see someone that does 600lbs in the leg press (that is good weight; not super heavy, but good), but go for 100lbs on the squat, that is nothing but an ego lifter showing off to people just because. Stay away from this people.
This one one of the most common exercises in which you see people ego lifting; they go
really heavy on the bench, but with a terrible form. The most common thing they do, is take out the barbell and go down to a position in which your arm/forearm are not even close to 90 degrees. Look; is you see somebody who is capable of benching three 45 lbs plates on
each side it will reflect in their body shape; wont be just a skinny homeboy walking around.
Going to the gym is not about showing everyone around that you are super strong or that you know a lot about bodybuilding; going to the gym is about doing the exercises with great form so that everybody can see your great body out of the gym. If you want to impress someone, you want to do it by building muscle, not by telling people that you can move a lot of weight.
Whatever you do; DON'T BE AN EGO LIFTER