Too add to this, watch a lot, and I mean a lot, of good form videos on YouTube. Find good YouTubers that have good form and watch them.  Too many times I'm at the gym and see gymbros not having good form and half repping everything.  For example, lat raises. If you go above your shoulder, then you are using your traps. Now it's not a shoulder exercise anymore. Try not to rock or use your body to move the weight. Another example, incline dumbbell chest press. I see bros all the time doing too much weight and only moving it a few inches. Wtf is that gonna do for you. Make sure you do the complete motion. No half reps, no half motions.  In all movements, go slow and controlled. Feel the full contraction in the right muscles for the movements. If you feel like you are using accessory muscles, check your form and remove some weight if needed. Watch. Your. Form. More quick examples: Do not drop your elbows in rear delt pulls. For dumbbell rows, try to focus on the back muscles pulling the weight, not relying on the contraction of your bicep to lift the weight. There are multiple ways to squat and deadlift, pick the one that is right for your body type. Etc. There is a lot to learn, but with diligence and time, you'll be able to be more confident in your lifts to add more weight.