Building your characters is one of the most important things in fiction writing. You have to have believable characters that people can connect with on some level. The fun thing is that there are so many levels that people can connect on.
There is that adorable, cutesie character that everyone loves; the annoyingly perfect girl that you love to hate; the comic relief of the group; the bad boy; the list can go on and on. The interesting thing is that you can mix these roles up into an infinite combination because everyone is different.
You also have the good vs. evil card to play. This too can be manipulated. Think about how many books, movies, TV shows you have read/seen where you root for the "bad guy." It happens quite often. There are many "bad guys" that you feel sorry for, and there are the ones that you hate forever.
This is where the Rambling Voices in My Head kick in. When I create a character, I decide upon who they "remind" me of. Usually it only takes one scene to start this off. I pick one or two specific qualities and base my characters on that for uniformity. There are times when I am in a silly mood, times when I'm in a cranky mood, serious, etc. By picking two dominate traits and adding a specific quirk, the new character has been born.
Just as in real life, the characters grow and develop... and this is a good thing. While you want consistency, it is fine for your character to occasionally do something "out of character." Everyone has moments. By connecting with how you would feel in a given situation, or a combination of people you have come across in your life, you can make your characters come to life. Everyone has had to deal with some sort of loss in their lives. We all have times when we are happy, sad, angry, frustrated.
By finding the emotional connection in body language and in all of the five senses you can show these personalities in your writing. It took me a long time to understand what it means to "show instead of tell."
Ex: The little girl jumped and squealed as she bolted for the ramp at the crowded playground. She stretched as far as her arms could reach, tottering on the edge of the decking for the painted metal bar. With all of the chatter and laughter of the children around her, she couldn't hear her nanny calling to her. Fearlessly, she swung along the bars to the other side, not knowing how close she had come to landing face first into the cedar chips that surrounded the structure.
I'm sure that just about everyone has seen a fearless, carefree child on the playground at some point in our lives. Perhaps that person was you or maybe it was who you wanted to be.
The next thing is to make your characters connect with each other. This doesn't have to be as scarey as some people think. Or maybe scarey is what you are after. Either way just keep the character's qualities in mind. You can have characters that blend together with similar or complimentary qualities or clash with their similarities or differences.
Draw on your own experiences for stronger emotions and remember that the sense of smell is the sense that has the strongest connection with recall. For instance, think about a skunk; think about the trash that sat out in the sun; think about an early autumn bonfire; think about Thanksgiving dinner with turkey, and pumpkin pie. I'm sure most of you could actually recall the smells as you read it. (that's why I ended with a pleasant smell.)
By drawing on emotions and the senses you can create friends and new characters. And by doing this, I hope that I can make friends with at least some of my readers. =)