Writing a Warriors Fanfiction: The Complete Guide

Plotting

Plotting is basically mapping out the order of events that occur in your story. It's been said a million times, but the basic rule is true: every story has a (clear) beginning, middle, and end. But this is better broken down like this:

Exposition - This can be a relatively short part, but it's an important one. The Exposition part sets up the story and our hero's motivations, and it introduces us to the major characters and the basic idea of how the world works.
Rising Action - Where the real story begins! The character is just setting off to meet their goal. There can be exciting parts in Rising Action, but it's not the most intense. The intensity will rise as the characters get closer and closer to the climax.
Climax/Conflict - The most integral part of the story. This is where everything introduced in the Exposition and Rising Action comes together in the final showdown. It's the hero's last chance to achieve their goal.
Falling Action - Essentially the opposite of Rising Action. Now that the conflict is over, things begin to die down.
Resolution - The end. How the conflict was ultimately solved. The end often shows the aftermath of the climax, and where the hero has ended up.

Of course, not every story has to strictly adhere to this model, but it's a good guideline to start off with. Let's use an example to see how this works. We'll use this model on the basic plot of Into the Wild.

Exposition - Bluestar gets the prophecy "Fire alone will save the Clans" as she worries for ThunderClan (after the battle at the Sunningrocks). Meanwhile, Rusty decides to explore the forest and discovers the Clans.
Rising Action - Rusty becomes Firepaw and trains as a warrior while trying to defy the kittypet stereotype. He meets some characters like Yellowfang and Ravenpaw while uncovering the secrets of ShadowClan (specifically Brokenstar) and Tigerclaw.
Climax - ThunderClan patrols attack ShadowClan and drive out Brokenstar, who Firepaw has learned at this point is a cruel leader. Brokenstar admits to his crimes, and Ravenpaw reveals that Tigerclaw killed Redtail.
Falling Action - ShadowClan is given a moon to find a new leader. Ravenpaw runs away to live at a barn. Firepaw covers up for him by telling Tigerclaw that he is dead.
Resolution - Firepaw and Graypaw become warriors. Firepaw expects to face Tigerclaw in the future.

After we've got the basic outline out, you could start planning what happens in each individual chapter. Nothing too detailed, just a basic idea. Example:

Chapter 1: Character becomes an apprentice.

This will make it easier to start the story, since you have a clear plan on what to do.