OK dude, here is how i usually do it.
When u bring the image in, first thing u must do is APPLY PAPER 2D, its in the same menu as the CREATE Sprite option, second, u must double click on the image so it takes u to the image context menu(forget what its called now, but just double click, then u must set your filter option to NEAREST. my sprites are crystal clear and this is the process i follow, good luck.
let me now if u come right dude