Which is in vogue now, for Teen Girls ?

I would like buy some apparel for myself. I prefer only Western Outfits like Jeans, Shorts, Tshirts etc. Please guide me in choosing the current rage. Especially, how should the Tshirts be - Short or Long ? Loose or Tight ? Plain or Patterned ? I am not sure. Also, I am a little apprehensive whether I can reveal my midriff and also my navel. Is it in fashion in India right now ? Please guide me with pics as well. I would be grateful.