XD Proportions are pretty weird, huh? Aghf, mostly it's a matter of just doing it constantly and taking note of when things "feel" too long or too short? Anywhere in particular? Like I said, I'm no expert but if I can help, I will!
So you're in New York, looking for jobs in San Francisco for when you come back? Well thankfully SF has a lot of little stores, and a lot of places are good with hiring students, I'm sure you'll find something!