How do I avoid circular dependencies between tables?

I think a lot of this would come down to the planning stages of an application if you are building a new one, mapping out the entity relationships and making sure the logic makes sense. Sometimes you have to take over applications that others built and don't have any control over how they designed it, in those cases try to understand the existing structure as much as you can, then plan out ways it can be optimized. Aim for a series of small wins that progressively enhance the application instead of one giant restructuring.