Saluton!
A good storygame, as Mizal mentioned, is a balancing act. On one side of the scale is the aspects of any good story - which is the plot, setting, background details, character development, that sort of thing. On the other side, a unique aspect of CYOA, is choice. A good storygame is, by design, a good story, but with multiple different outcomes. I will probably post a thread about it later.
Anyways, welcome to CYS! As Mizal said, reviewing stories is an amazing way to earn points and respect. If you're starting out, the short stories written in Creative Corner is a good place to start. I look forward to seeing your progress!
Also, a quick warning: Do not enter a contest without knowing how difficult writing a storygame is. If you miss a contest outline, you get SHAMED, which is truly undesirable. Trust me.