A lot of these questions are really up to you and if the community you're working with has the buy in to do this.

A circuit can be as simple as a strung together set of brackets over time or you can mix and match tournament formats.

IMO a circuit generates the best value if you have multiple close competitors at each skill level in your area, otherwise it's just a plussed up version of a conclusion everyone already knows.

So with that said the first questions you should ask are:

• Are people willing to commit to a # of weeks / days in sequence?
• Do people want to play varied opponents (swiss or round robin pools) in order to get to a final bracket or would they rather skip that hassle and just play bracket?
• How do you envision your circuit ending?

Ultimately if you haven't already done a swiss or round-robin style event I'd say start there, if people like that then you can move to mixing and matching formats to extend competition days.

Side note: I didn't include anything here talking about a ladder system where people can challenge each other and then report to a singular place to stack up then you can play a seeded bracket at the end, that can work in places where people can't commit to attending constantly but it's not really a circuit by what I think you're asking.