remove the headlights...
Four bolts at the top of the grille....
all of the screws holding the lower valance to the bumper cover along the bottom....
a couple screws holding the inner fender liners to the sides of the bumper cover...
Then there are three rivets at the top sides (on each side) of the bumper cover (visible after removing the headlights)....
If your bumper cover has ever been removed before, they may just be plastic push pins or something. If they are the rivets, you can pop them by prying on them, or just drill them out....
When you're reinstalling it, make sure to the get the corners into the lip (you should be able to tell what I'm talking about once you see it), and you can just use some of those plastic push pins where the rivets were to hold it in place.
After all of that, you should be able to pull the bumper cover off and get to the four screws on the bottom of the grille.
It's not super hard, just a lot of little stuff. I've got a grille sitting in my garage that I bought over a year ago that I haven't installed on the car yet cuz it's gonna be a pain in the butt. lol.