How to build up the cause of action?

In easy words, the cause of action (COA) is a set of circumstances which brings the P to sue the D and the P is going to win. How to build up the cause of action? (without fabrication).

(1) get the evidence
(2) prove the fact
(lawyers should be able to take up the case, confident and win the case)
(3) Client: full story A to Z (whether there is a COA or not)

Example:

~what is the law to be applied? - Law Reform (Marriage and Divorce) Act
~Under section? Cases? What the remedies? (divorce or damages(money) )

~ Is there any gaps of facts that the client didn't tell? (if so, persuade client)

So, for the brief :

(1) summary

(2) structure frame

(3) fact

(4) evidence

(5) relevant Acts

(6) cases

(7) remedies

At the end of the brief, is there a cause of action or not? If no COA, forget the divorce! haha.. (because the court cannot provide any remedy if there is no COA).