Tip 1: Be Unique
Words like kind, friendly, cheerful = Total paths to a Gary/Mary Sue! Plus, they are just overall boring! A vast majority of average, middle class people are relatively nice and friendly. If you want to have a kind, yet unique, character, bring out a specific type of kindness. Let's say, instead of saying 'Melissa is kind and generous', we could say 'Melissa has an overall kind personality, but she's exceptionaly generous. She gives all she can to help benefit others, especially the less fortunate.' See? That gave Melissa a more interesting personality because it focused on a specific instance of kindness.
Tip 2: Stereotypes,
or 
? In the real world, stereotypes are a horrible, horrible thing. But they can prove useful in RPs and stories. However, there are some bad stereotypes that many writers and/or RPers are prone to use. And that's because people who create children's movies (especially for young girls, e.i. Bratz, Barbie, Polly Pocket, etc.) generate phony stereotypes that lack true-to-life attitudes. Let's look the two most common examples.
The home-coming queen
Many stories depict the home-coming queen/ cheerleader/ clique leader as being a blonde who's obsessed with pink. Very untrue. The REAL home-coming queen should be a slim, tall, tan girl with pursed lips and super-chic, super-expensive designer clothes. She should carry around a steaming hot soy drink and should stroll down the hall with her girlfriends. And another tip, sometimes the home-coming queen isn't even like this at all. Wouldn't you think that the most popular girl ever should be the bubbly, witty cutie who wears enviromentally safe boots?
The nerds
Everyone thinks that a nerd is someone who has buck-teeth and wears wierd clothes and likes math. Nuh-uh. Nerds are people who, despite being over 8 years-old, still like Pokémon. And know the difference between manga and anime. And talk about RP in the corner of the cafeteria and who cover their comics in a plastic coating. Nerds are not buck-toothed brainiacs.
Tip 3: Be un-expected
In stories, nothing could be more dull than when the herione marries the hero. It's SO obvious! For a good story, and a good character, add unexpected plot twists and unforeseen romances. Instead of the guy marrying his girlfriend, maybe let there be some kind of an arguement. Seperate them for a few chapters, or maybe even a few books! Instead of letting the girl's crush ask her to go steady, maybe let her venture out and find a new crush for a bit. Make sure nothing's completely certain, unless the characters are married.
