Many people think that one should neither blow, nor pinch out a candle. Blowing will blow away your good luck, and pinching will pinch out your desire.
I disagree; a large part of spell work exists to put you in the right state of mind to be able to perform magic. It depends how you interpret your actions. I’ve never thought of blowing out a candle as being in any way linked to blowing away luck. To me it represents sending my spell on its way; giving it an added energy boost and seeing it off.
I do see pinching as extinguishing luck – that is what it looks like to me – and in the same way, I see using a snuffer as dampening and extinguishing the spell.
My point however, is not that blowing is the correct way to do it. The point is that that is what makes sense, and has meaning to me. If you interpret the action differently, you can choose do things differently, because it will be more useful for you that way.