Developing large muscles is something that a lot of guys like myself want to achieve for our physique in order to attract beautiful women.
This is my interpretation of what I think it takes to look great in the mirror.
Weights are your best friend
Using weights in an effective manner can drastically increase the way your muscles tone out and look to others. Go about lifting weights through both speed and mass. If the weight is heavy, you can curl a bit faster; if it's lighter, go slower so that you build tension in your muscle fibers which in turn will help stimulate your body and tell it to improve itself to help adapt to your environmental change.
RPE
RPE refers to this idea of how many reps you have "left in the tank", meaning how many more reps you can do before you give out. Usually when you're working out, you've likely encountered the habit of stopping your set a bit early because the initial experience of tiredness makes you feel too lazy to continue. In that regard, you can help measure out your rep experience with the following scale:
RPE 1: 9 reps left
RPE 2: 8 reps left
RPE 3: 7 reps left
RPE 4: 6 reps left
RPE 5: 5 reps left
RPE 6: 4 reps left
RPE 7: 3 reps left
RPE 8: 2 reps left
RPE 9: 1 rep left
RPE 10: 0 reps left
You don't always have to max yourself out at RPE 10; sometimes it's even a bit better to stop at RPE 9 to make sure your arms don't give out so quickly in the gym because to be honest, I always feel a bit embarrassed when I go into the gym and physically kill my arms 15 minutes in because then I look like a wimp even though I have large muscles. Also, random FYI: my profile picture is not me; I just admire that guy because he's hella muscular and I wanna get like that some day.
Overall
Just keep yourself going at a good pace and find a balance between how much you're lifting and how fast you're going through each rep. The longer you fight gravity when lifting back down, the more built your muscles will become.