IF YOU WANT TO BE A WRITER, BUY THIS BOOK:
For my quick advice, here are the rules my Storytelling teacher has hammered into the class's brains. These rules can obviously be broken if you're feeling inventive, but your story will ALWAYS be successful if you hit all these.
Involve your audience immediately
Have appealing heroes
Have compelling villains
Every story must have conflict
Leave your audience wanting more
Do not set something up and not deliver
Tell the story as if your life depended on it
Conflict is any problem presented. It can be mundane or life-threatening; physical, emotional, or psychological; comedic or tragic; it just HAS to be there.
For the not-delivering part, if you go through the whole story saying "boy, it sure will be terrible if that kid drops the vase," and then the kid never drops the vase, you'll piss people off. They were waiting all this time for when he would drop it, and you let them down. Again, this can be broken, but unless you're a genius or you have a ton of experience, follow the rule.
Making a character appealing depends on the story you want to tell. An easy way is to make them cute or charming; that works for Pixar, and it has been working for Japan since the beginning of time. The second-easiest way is to make them cool - someone your audience looks up to. However, a truly unique character is going to take a lot of thought. You might even have to come up with their whole life story.