Let me begin by throwing out this disclaimer: I do not consider myself an expert in the craft of writing. I say that because I am about to give you some words that relate to character development and the words will reflect how I do it. They do not make it the "right way." The "right way" is ultimately "your way."
First of all, I am a bit of a "pantster." That is, I fly by the seat of my pants when I write. If I am going to outline I more than likely do it after the fact. Probably not a good thing but, it is me. Many writers
have character charts and they may profile a character before they begin to write about them. They want to get to know them first. For example, they may list: male/female; height/weight; age; ethnicity; hair color; eye color; single or married; child or teen; religion;; education and so on.
When I get in the writing mode and words begin to pour out of my pen onto the paper, (yup---pen & paper, the keyboard comes later) all sorts of thoughts start floating before me. Many may consider that a chaotic way to develop a story, no less a character. But my main character is in my head already. I know him/her. Their development and personality is almost a given when I begin. As I go along, this person has to interact with other characters in the book. Many of these characters just happen to come along, unexpectedly, as I write. Then, having met them, I begin to know them. For example, in "The Priest and The Peaches," the character of "Fadeaway" Walker shows up. I have no idea how Fadeaway came out of my pen. But---he did. Suddenly he is a pathetic -0 year old, sort of a lost soul, soft spoken and gentle. But his incessant visiting of the local taverns never having any money and trying to get someone to buy him a drink has turned him into someone most of the guys despise and want to avoid. But then "Pops" comes along and all of that changes. There is a poignant scene at Pops' wake when Fadeaway quietly steps to the casket and slips a pint of whiskey under the lid. Tears coming down his cheeks he whispers, "Thanks Yimey, Happy New Year." No one sees him and he leaves.
The point is, Fadeaway Walker came along unexpectedly and I ran with him. I never planned on his showing up but there he was. So, that is how it goes with me. I will admit that sometimes so much stuff comes out of my pen that unscrambling it and figuring it all out can be quite the challenge. So, if it works for you, develop a character chart and use it. Outline first if you must. Here is one thing I do know; we are all different so we must do our work in the most efficient way possible that fits who we are. Ultimately, we all have the same goal, to be able to write "The End."