I got good idea to old games sprite!
Why draw own tiles, take old nintendo game pictures from net/
or if you have nintendo games in your computer play game and when you find cool place take screen shot!
Then go to paint, copy your picture over your tile "bottom" and if it is too small it isn't so hard to draw more parts to pic by yourself cause nintendo uses small capasite of colors
best pics from net found by google searching from images at game name of game you want! easy huh?