Storytelling has had a formula for yearsAndYears. Some people speak of it in disdain ("it was too formulaïc") and others (creative writing and intro film teachers, mostly) praise it. Everybody else (us) is a sucker for it.

Here is the literal formula, in pseudo code:

{A} 
{A} Reinforced

{Z}

{A} Returned

{B...Y}

{Z} Returned

You can (and should, because it's free and you can throw out your work if you don't like it) practise this formula by plugging in events to represent A and Z, where A and Z are polar opposites.

Really obvious examples are any given romantic comedy:

{A} Jack is A="single and free"
{A} Scene to reinforce that Jack is in relationships with no strings attached. Jack is {A}.

{Z} Jack meets Jill, realises she makes him happy. He decides he's had enough of being {A} and want to be {Z=married}

{A} Reunion with old school mate makes Jack question his resolve. He leaves Jill so he can be {A}

{B...Y} Plot happens. Jack does stuff, Jill does stuff. Funny? Tragic? You decide!

{Z} Jack realizes at last that he's only happy with Jill, and that being {Z} with Jill is the only way to be truly free.

You can also try it with the old Evil Empire plot line.

{A} Jill is an {A=obedient citizen}. Loves her mama, loves Jesus and America, too.
{A} Scene in which Jill witnesses a Rebel being mistreated unjustly, but does nothing to stand up for what is right, because she is {A}.

{Z} Jill meets Jack, an outlaw and rebel against the Empire. He's in trouble, so she helps him evade the police.

{A} Jill, horrified at her own rebellion, conforms all the more. She is dedicated to the Empire, and works diligently to hunt down Jack and his rag tag band of rebels.

{B...Y} Plot happens. Action, laser guns, laser swords, nationalism, motorcycle gangs.

{Z} Jill, seeing the devastation her allegiance has caused, realises that the Empire is actually Evil. She joins the rebels to fight for freedom.

Now go practice this. Soon you will be telling stories, jokes, and anecdotes that have a clear beginning, a clear conflict, and a clear ending.