There are mountains of information out there, how much protein do I need and how much cardio do I need, and how much of a surplus do I need. Are all great questions, but heavily debated. Two things do remain true though. You need to create a mind muscle connection. Just grabbing the weights are throwing the, is terrible. You have to pay attention the feeling of the muscles contraction and lift with the intent of making that muscle work. Otherwise you could be loosing that specific workouts efficacy because you thrust your hips or just plain old do it wrong. There is a perfect form and you must learn it.
You have to understand that your goals must me measurable. A scale that can measure your body fat is essential as it will help tell you if you are reaching a plateau.
My favorite person on form on youtube is Jeff Nippard. He talks about everything from supplements, diet to the anatomy and form used in different lifts. He is a personal trainer for free, and alot more educated than the guy selling supplements at GNC whose probably on steroids. Click the link here to listen to him talk about the perfect form for bench. Something that does not come easy.
He is a great resources, and it is still very easy and possible to hurt yourself. This is especially true for the beginning, weather you have been out of the gym for a while and therefore weaker, or a complete newbie, these videos will help you perfect the form.
Another important aspect of these lifts and forms, is that, if you are new, its obvious to the more seasoned at the gym. So, you are fully welcome to ask for help. Just do it in such a way that he is not upset. More often then not, these guys are very warming and welcoming. Even if its only for a 135 bench, they would be happy to help spot you.
The Next most important lift you will ever do is the Squat. The squat requires alot of attention to detail. If you do it wrong once, you can really hurt and strain your back. However, if you do it wrong consistently, you create greater problems for your back. Again, here is another link to Jeff’s squat routine.