How to develop your cities - businesses

A lot of people have trouble coming up with businesses for their cities. I mean how many butcher shops or blacksmiths does a city need? The way I like to do it is to pick a kind of shop and then figure out how they might be different. In writing up how they are different, you will know what they are like.
OK - An example seems to be in order: I thought that the city needed some form of elementary education. Where were these kids learning to read or write before they went to those big universities? Well - a lot learned from tutors. I haven’t fully developed all the tutors yet, but how are they different? Well, some are strict and some are easy. The easy ones might simply be weak of will or they might be sycophants who want their rich employers to think they have brilliant children. That’s at least three tutors right there.
More importantly, I created two schools. How are they different? Well, just like in our world, one is secular and one is run by a religious order. Therefore one is in it for the money and one is in it to better the community. This also changes which classes they will teach or at least focus on as the religious one is definitely going to stress religion or theology. Both teach the three “r”s, but the secular one will get the children into much higher mathematics, because they are being trained for business. Likewise, the religious school will be teaching them more poetry and music, because their religious services include these. Both are strict, but the religious school is stricter. Why? Because the secular students are customers; the religious students are members of the flock, and their parents don’t want to be embarrassed in front of the local priest.
This compare and contrast works really well when you’re trying to come up with businesses. The more differences you can come up with, the more stores and shops you’ve just described. Good service or bad? Merchandise made here or brought in? Clean or dirty? High end or basic? If it’s a leatherworker, does he only work in cow hide, pig skin, lamb skin or horse hide? or all of them? If he’s a smith, does he work only on tools and ag (agricultural) based items or is he more interested in machinery? Is he secretly dreaming of being an armorer, but never got the chance? Even if you just come up with one business, think of how it could have been different, and you’ll likely have one or two more written up!