To start writing your 'Harry Potter fanfic', begin with research. Reread the books to get a good grasp of the world, the magic system, and the characters. After that, brainstorm ideas. You could start with a 'what if' question, like 'What if Harry had been sorted into Slytherin?' or 'What if Voldemort had a sister?'. Once you have an idea, make an outline of the story, including the beginning, middle and end. When you start writing, don't worry too much about grammar at first, just get your ideas down. And make sure to have fun with it, because that's what fanfic is all about.
Well, starting a 'Harry Potter fanfic' can be exciting. You should first choose the time period you want to write about. Whether it's the early days of the wizarding world, the time of the original series, or a future time. Then, think about the themes you want to explore. It could be friendship, love, power, or something else. Consider the characters you'll use. If you want to use the main characters, think about how you can develop them further. If you want to create new characters, give them interesting backstories and personalities. Also, build a world around your story. Describe the settings, the magic, and the relationships in detail so that your readers can really immerse themselves in your 'Harry Potter' inspired world.
First, you need to have a clear idea. Decide if you want to focus on a particular character like Harry, Hermione or Draco, or if you want to explore a different part of the wizarding world, like a new magical creature or a forgotten corner of Hogwarts. Then, think about the plot. It could be a new adventure during the school years, or something set in the post - war era. Next, create your own unique characters if you want to add to the story. And don't forget to keep the tone and style somewhat similar to the original books so that it feels like it belongs in the 'Harry Potter' universe.