If you need a perfect result, don't buy this, go to a body shop, there is no perfect solution without sanding, filling, using computer matched paint and spaying for several layers.
I had no experience in doing touch-up paint, but still managed to achieve the result I'm satisfied with (with really LOW expectation). I didn't do sanding first, because I don't want to cause more damage to the paint, instead, I applied a few layers (wait for 10 minutes between each), then used the paste in the kit to buffer it out. In the instruction, they did say if your car is very new, the color is likely mismatched (the paint is more likely made for aged paint), which is my case, you can definitely tell it's "too white" in certain angle, but it's barely visible from few feet away, and most importantly, it covers the metal and prevents the further rusting, I'm satisfied with the result.