*Use the Thesaurus and the Dictionary to find new and exciting words to use in your stories.
*Use analogies! "The sun shone down and made the world feel like the inside of an oven."
Try to use a word in a way that it's not commonly used! "On this cloudy afternoon, her kisses feel like the rain, sad and slow and soft and moist." However, using analogies just because you think they sound poetic usually doesn't work very well.
*Make it funny! Use puns and irony to your advantage, or put the characters in bizarre situations. GIR-like randomness (for those of you that watch Invader Zim) is also quite humourous if you can pull it off right--try it and find out!
*Use no netspeak in your story! Save it for comments and chats if you must. It DOES NOT MAKE YOU COOL! This means no LOL no ROFLMAO no WTF no L33T and no using 2 or U or any other "convenient replacements".