What kind of character do you want?

First things first: this is your story, so it should include the things you are interested in. If you don't like tragedy, don't write about that. If you love amoral characters that get themselves in nasty situations, write about that. It will be easier to start and to finish if you have an idea of the kind of story you want to tell.

Stories can be a character-driven story, or a plot-driven one. If it's character driven, then you really want a well-rounded character at its center, and also interesting side-characters if the story calls for them. If it's plot-driven, then you still want your characters to make sense. If you have the kind of characters your plot needs, your story will move along smoothly.

Name and Age

These work more as identifiers than anything else, but they still convey certain things about character that can be fun to explore. Writers are the only people besides expecting parents who frequent baby name websites.

Names don't need to have any deep meaning or connection to the story. In reality, our names are usually out of our control, so they depend on the kind of people your parents are. Did your character's parents choose Aliyah because they thought it was pretty? Or maybe their mother was an eccentric hippie who named her child American. Finding a fitting name can help you build the setting of the story.

If your character decided to change their name later in life, that can be a whole story by itself. Maybe they were running away, or are transgender. Most of the same question as before apply in this case.

Age is much more straightforward. It's important because it gives the character a certain amount of lived experiences, but above all it gives the reader certain expectations about how the character will act. Readers will think 'a 25 years-old man shouldn't be acting like a 14 years-old boy'-- but that's not always the case. Which expectations you break or keep is up to you.

Backstory

Think of all the parts of your character's past that were out of their control-- these are some of the most defining elements of the character AND the story.

Start by the basics: place of origin, ethnic heritage, what kind of environment they grew up in, and any significant experiences. Where they taught to be very religious? How did the people who raised them treat them? What part of their community were always at odds with your character? Then ask yourself: what were the consequences of these things?

A back-story is not necessarily the first step to creating your story. You could start with any other element and work your way backwards, but defining the character's background will give context to the current situation.

Personality

The very base of a character, but something that can be hard to define. After all, can you say a person is wholly 'optimistic', or 'kind', or 'sarcastic'? These are merely base traits and flaws of a person, but adhering to them too strictly can be restrictive.

Think of their personality in terms of attitude. Do they give up easily in the face of hardship or do they think that as long as they have help they'll be fine? Do they know how to appreciate good times or do they not realize what they have? Determine their likes and dislikes and what the character does about them. If they're artsy people, are they willing to make a career out of it or do they consider it only a hobby? Are they distrustfull of people who like dogs?

The most important thing about their personality is that you have to show it. If your character is judgmental, show how they evaluate the people around them-- maybe they take academic achievements very seriously, or distrust people based on appearance.

Character arc

People change. Readers consume stories to travel a road with your characters, and see where it gets them, otherwise the story will feel pointless. Take the elements that have been mentioned and ask yourself: what does this person want? Your story will show how and why the character gets what they desire-- or don't get it. Or it will show how what they wanted was the wrong thing. The most important thing is to show how a situation changes the person.

The change can be huge, or minimal. It can impact only the character, or their entire environment. Maybe the character isn't even conscious that they've changed, much less consciously tried to change during the story. Think about yourself-- it never hurts when you're writing-- think about a situation that you thought was an annoyance, or a great luck, how you saw it at that moment, and how it truly ended.

Nothing exists in or comes from a void. If a story or character development does not make sense within the context of the story, readers will lose patience. If you want something specific to happen, then think through how that comes to be. Fiction works like hindsight does-- it's all obvious when it's all said and done-- but to your character, things are still happening. Write your character as they live in their present.

Always remember that just because you write something at the beginning, it doesn't mean that it's set in stone. If you're having trouble writing a scene or creating a character-- change it! Creating characters and stories is a process of discovery. Keep thinking, keep imagining, have fun with what you're trying to do.