How do I get the best picture on my 46" LED tv?

Hi everyone I have a 46" 1080p 120hz Sharp aquos tv the quad quore technology stuff.so I've web trying everything just to make it look like the one in the store.and I tried turning on the 120hz and it didn't seem to do anything so could you please give me some tips it would really help me.I love to watch movies on it expecially Avatar on blu ray.so i would enjoy it more if it was at it's best setting thank you for you help!