One of the most common questions we get when initially configuring a Studio or City is “Should I make this piece of information an Element Type or a Property?” This is especially confusing when the information to be added is to be constrained to a list of possible responses.
I've been designing city schema's for Exaptive for many years now and often (and unfortunately) the answer to is "it depends". There are several ways to go about this and I've tried to list some of the reasons you might choose one way or another in the following article: Multiple Choice inputs: Dropdowns, Autocompletes, and Radio Buttons.
In that article, I describe:
If you're looking for help of a more technical nature, how to create property fields or connection fields, check out these articles:
Properties on Element Types
If you're looking for some quick information and don't want to read the whole article, here is the quickest synopsis I could come up with: