Reddit reviews Plot Versus Character: A Balanced Approach to Writing Great Fiction

There are hundreds of books about this. I recommend this one. Try starting out with an archetype and flesh it out from there. I've heard of using the Meyers Briggs test to create a basic personality type (actually, I think I learned that from Plot vs. Character). Give them a back story and determine how certain events in their life would cause them to behave. For example, if they were abused growing up, decide whether your character becomes a bully or if they have taken every precaution to ensure they would never harm someone smaller than them.

In reality, there's no quick and easy approach. You have to spend a lot of time picking a fictional person's brain. That's all there is to it. There's an infinite number of ways to do so and none of them are wrong.

Plot Vs Character by Jeff Gerke is good one:

https://www.amazon.com/Plot-Versus-Character-Balanced-Approach/dp/1582979928

Plot Versus Character by Jeff Gerke is pretty good. Getting Into Character by Brandilyn Collins is also good.

I highly recommend Holly Lisle's Create a Character e-book. She covers the process of character creation in depth. The e-book also includes tons of questions that really make you think hard about your character's personality, background, motivations, compelling needs, etc.