When sculpting your arms, it is important not to forget your triceps, which account for about 60% of your upper arm mass. It is impossible to build competition-ready arms with only a bicep workout. For triceps, do tricep cable pushdowns, overhead extensions, French curls, and tricep kickbacks.
It is also important not to lift at your absolute capacity; to build great muscles, form, finishing your sets, and range of motion are paramount. Getting out of the mentality that anyone is watching you at the gym is the best thing you can do for yourself. Rather than trying to impress others with what a large weight you can lift using poor form, short range of motion, and putting the rest of your body into the workout, remember that no one can be impressed who isn’t watching. Because they aren’t. If they do happen to be watching, more likely than not, they will be mentally criticizing your form, laughing about how to tough you think you are.