Still talking about making your first Game and the guidelines to take care of
Make a relation between the player of the game and the character inside it. Build up your game character before you tear them down. Make their loss count. Try to bond the your game player with the characters to feel the loss when it happens
Try to know the motivations of your game character (what does the character is trying to do and why), that will help you determine what your character should say / act and will result in much richer character. for example, a prince trying to save his princess should be in hurry , impatient guy, he don't stop to open a treasure but he kicks it to open it, he jumps right into a fight and kill enemies in a hurry.
Naming your character is a very important, Names carry weight, it is important to give your character the right name. Baby books are a great place to start looking for names. try to find names that have some significance to the character personality or what their occupation. and Most important never give your character a name that gives away the ending of your story, ex : don't name it devil killer :)
When making a game for kids make sure game don't suck, most common mistake while making a kid's games is making its story very simple, consider stories from kids books, if it is good enough for a kid's book , it is good enough for kid's game. another advantage for making a game for kids it that you can teach them stuff while playing That can be called "edutainment"
Stay tuned up for Episode 3 :)