Creating characters is one of my most favorite parts of writing! You are creating a being straight out of your imagination. But this large of a task can sometimes feel daunting. Here are some things that I find are the most important aspects of creating a character as well as some tips on how to ease the process.
First of all, your character's name is IMPORTANT. Don't name your character until after you have thought about the other traits of your character. The name should act as an accurate representation of your character. The naming process takes me hours for the main character. That is because it is supposed to be so memorable. Even when naming side characters and flat characters, time needs to be taken to consider what their name represents about them. Use naming dictionaries and look up unique names so that your characters will stand out.
Make sure that your characters have well-rounded personalities. No one is perfect. Everyone has strengths and weaknesses, even the villains, and even the heroes. By creating characters that have apparent weaknesses and strengths, you are creating more human characters that your readers can relate to. Making these personalities compliment and contrast each other, you make more natural conflicts and solutions. This creates a story that is more exciting as well as more believable.
Characters grow and change after different situations. Allow growth to happen. Don't be afraid to allow your character to change as they develop. This may mean they aren't as fun or adventurous sometimes, or maybe they grow into more of a risk-taker. They may also grow from child-like to more of an adult. This will not always be easy or fun, because growth often means hardship for your characters.
Finally, remember that the character is their own person. You, as the writer, are just following their story. Try your best to not map out every individual moment of their lives. It makes it interesting for you as a writer and for your readers. And have fun when creating your characters. They are the ones that build your world and your story more than anything else.