I'm writing a YA fiction book. How do I make the character different, yet understandable, and what are your suggestions for keeping track of information you have placed in your book? For instance a timeine or smthg like that.
The question of layered characters is a big one. Basically how to write characters in general, but here are some things to get you started:
Goals and motivations
Give all your characters goals and motivations, even the small ones. Maybe the taxi driver is driving his taxi not to make money driving customers but to get social interaction? Use goals and motivations to break out of clichés. (So maybe the taxi driver then rather drives his cab to prove his thesis for his manifesto: that mankind is evil and needs to be eradicated...)
Give the more complex characters values. Especially helpful if they have conflicting values. E.g. being a good parent and being a paid author. There's room for some drama when trying to make those two work simultaneously. Here are more examples of values to get you started.
Some select characters could be much helped by having an emotional wound in their backstory. I find they really make you understand and see a character come alive.
Organizing your character and world data
I always spend way too much time planning and outlining my texts, and then, when I start typing, something happens at the tips of my fingers and plans need to change (ok, most plans don't survive that meeting with reality). So I generate information before the writing and then while I write.
So my answer would be to use what you think will work, don't be afraid to change if it doesn't work and try to keep it all organized in the oldest and safest system in computing (files and folders, backed up and kept in some cloud drive like Dropbox—I use DokuWiki because it keeps its data in files than I can backup and read even without DokuWiki if the worst should happen).
Keeping characters different; write down your characters traits and have it nearby. When you have another character idea, write it down as well and compare it with your other characters. If it's the same or close to another character, you should probably just tweak the existing one. Of course, you can have people who are pretty much the same(ie Fred a George in harry potter), which can be useful sometimes.
Making it understandable; If you don't understand your characters, then the audience probably doesn't either. I would recommend reading the story through but imagine you know nothing about the story and are just reading it for the first time. If you have a hard time with this, beta readers will be able to help.
Keeping track of information; Write it down. Of course, you should be doing this when you're writing the story, but it helps to have a sheet with the main points on it for easy reference. If you need to go back for a quote or something, then you'll have to browse through your story to find it to make sure you're quoting it right.