Stone chip touch up paint

[tigersargyle]

I have just found an annoying small stonechip on my A4 Avant front spoiler. Its actually caught the plastic rather than metal and seems to have gone through the paint. My car is Ibis White and the spot is black (like a engrained squatted fly!). Fortunately its very small (pin head size), but still noticable to me!

I have purchased the Ibis White pencil touch up stick set (clear coat and base coat). Does anyone have any tips on how best to prepare the surface and apply the touch up paint?