It might be overkill but when I first started driving stick, I would heal toe through all the gears when coming to a stop. It's a lot easier to learn to do it while just slowing down and you don't have to worry about your speed for the turn ahead. It's all about practice (in a real car) and soon it will be second nature.
More importantly, you haven't driven a manual car, you should probably be worried about the basics, like not stalling when starting in 1st gear and shifting up through the gears smoothly. The M3's clutch is not going beginner friendly. You should practice on a friend's car before you get your M3. You don't want to look like an idiot when you can't get your M3 into 1st gear.
