One very important thing to know: If you are not making the game in retro stype pixel art mode, you'll want to make your tiles 1 pixel taller and wider than the grid size....in other words, if your grid size is 32x32, make your tiles 33x33, with the anchor point at top left.
This will cause an overlap of 1 pixel...otherwise, you'll get hideous seems showing up between the tiles! (Due to HWA filtering etc)
best of luck.