I did this a few weeks back and wanted to add a few things:
1) sometimes just loosening the pins doesn't cause them to come out of the rubber boot, but you can use a hook or flathead screwdriver to push them out once they are unscrewed
2) the rear anti-rattle clips are much easier to remove and replace than the front ones
Important:
3) I had to compress the pistons more after removing the caliper because the new pads were significantly fatter than the old pads and therefore there wasn't enough clearance to put them back around the rotors (which I had also replaced). The common brake piston tool doesn't fit in the E9x FRONT M3 caliper (but it does fit in the rear caliper, unless I was doing it wrong) but the 8" C-clamp did fine. However be sure to compress the piston very slowly, because if you do it too quickly brake fluid will leak from the master cylinder, and if that happens the brake fluid can ruin the vacuum sensor and put your car into limp mode. If that starts happening you will need to replace the vacuum sensor.
That's what happened to me btw: I compressed the front driver's side caliper too quickly, brake fluid leaked but it wasn't so much that I was concerned so I forgot about it. Then a few weeks later I kept getting a loud buzzing sound from the front of the car. Turned out the leaky brake fluid ruined the sensor. This is not uncommon and there are a few threads about it. Here's one:
https://www.m3post.com/forums/showthread.php?t=1338052