i'm not bad at writing, but i've never laid out a storyline, or anything large-scale at all, in my whole life. writing the story for 3 different games... it's going to be hard.
Well see it doesn't have to be the fucking Da Vinci Code plot-wise if the style and characters are on the cartoony side. You gotta know the style of the game and what kind of dialogue/plot ideas are appropriate for said style.