The beginning was very confusing. The shelf highlights looked like lights so I ignored them at first. The purchase dialog seems to work arbitrarily. When I approached the granny, she gave me the "Taking a break" dialogue so I thought that was all she had to say and only found out about the tutorial midway through the game. When I figured out how to sit down, I thought the customers approaching me with items above their heads was them purchasing things instead of them complaining about a lack of items.
I hope all this critique doesn't come off as too negative. I did enjoy the game after figuring everything out after a few minutes. For your first game, this is quite well done :)