One thing - they sometimes provide this stuff in 'color'.
Don't do that - it's all kinds of wrong...
And - use sparingly, since it can give the feel of 'weight' on your upper lip, and if there's something 'weird' going on, it's likely you'll play with it.
Unless your Impression is that of 'Snidely Whiplash' - that just draws unfavorable attention to it, and since we're on that topic - be sure to keep it clean.
'Pinaud' used to provide a small moustache comb along with their product, but any fine-toothed comb will work, and a small hairbrush will work even better, since it has the tendency to get the disparate hairs to sort of twine together.
Vaya,
Scouts Out!