This cat is a potato, surfing.

So, there are some other ways to create stronger characters. These are things that you can work for your writing or while you're writing.

Know your character's backstory. Write it out, think about it, have an idea! If this means developing your world a little better, that's a good thing. You don't have to break down their childhood or anything unless you really need to, but at least know where they're from and where they're coming from.

Speaking of which, know their motivation. Be sure you know WHY they do what they do. It might be because of a plot in the action of your story, or it could be influenced by their backstory. Probably some of both!

Consider their likes/dislikes. Does anything stand out? Do they have any quirks, notable preferences, or fears?

HOW do they speak? People have their own way of talking. This isn't limited to an accent, but to certain words they use based on their experiences. Are they casual or formal in their speech? What do they talk like under pressure? What about when they're afraid or in front of an audience? How well do they know the language they speak? What is their education?

How do they enrich the character drama? Before you add any character, know how they mesh with your story and your existing characters. If you're working on characters at the outset of your story, be sure all your characters compliment each other. Either way, how do your characters draw out each other's stories? For instance, someone who is reticent and shy is brought out by someone who is extroverted or flirtatious.

Pilot write them. Sit down and write a little bit in that character's voice. Write them in simple situations to break them in. Your story can be a sandbox, but don't let the place get too messy! You don't want to regret starting your character one way and not being able to justify their direction another way.

So, now that you have your super strong character, how are you going to introduce them into your story? Well, there's only one way...