Voice

Voice is always this really vague concept that authors throw at you. Kind of like voice is something no one know how to harness and no one knows how to explain, but once you find it you'll know. There are a couple of things I've found that I can associate with voice.

Changing cliches to fit how your character would see it: 

This one is from the point of view from a twenty-three year old woman:

My heart is beating so hard I think I might break my bra strap.  -- Paige Torn by: Erynn Mangum

See how she did that? Taking the simple, overused, highly-necessary description of the heart beating when scared and added the breaking-of-the-bra-strap detail to make it fresh and different.

Little details that only your character would notice: 

This is from the same book, same character.

I was watching Flynn Anderson--who had no similarity to Flynn Rider from Tangled--wrestle with our copier. -- Paige Torn by: Erynn Mangum

Not everyone would associate the name Flynn to a movie. It's just the way Paige interprets things.

Take your character's age into mind: 

This is from To Kill a Mockingbird, in which the main character is an eight year old girl:

Mr. Avery was red in the face from a sneezing spell and nearly blew us off the sidewalk when we came up. --To Kill a Mockingbird by: Harper Lee 

The way she said it gave you an idea of her age, considering that she's small and tends to over-exaggerate things. 

Using similes based on events that only in your story: 

This is from To Kill a Mockingbird, too, in which the Radleys are people who never come out of their house:

Every wood door in the neighborhood was shut as tight as the doors of the Radley Place. --To Kill a Mockingbird by: Harper Lee

 This one is referring to a person she thinks is incredibly uninteresting:

This thing has more personality than Peter and his parents combined. -- Paige Torn by: Erynn Mangum

Dialect: 

I asked her why the roads were red and she said she didn't know and for pity's sake, not to ask her anymore questions. -- Anne of Green Gables (the movie)

I imagined how it would be: when it happened, he'd just be sitting in the swing when I came along. "Hidy do, Mr. Arthur," I would say, as if I had said it every afternoon of my life. "Evening, Jean Louise," he would say, as if he had said it every afternoon of my life, "right pretty spell we're having isn't it?" "Yes sir, right pretty" I would say and go on. -- To Kill a Mockingbird by: Harper Lee