Occasionaly during a shave I have a bad habit of adjusting my grip or turning the blade while it is very close to my face! I usually catch the error wide-eyed and think to myself "Kee-rist!" if that had touched me it would have been a helluva alot more than a nick to deal with! So I try to make a concious effort to stretch out my arm a little when manouvering the blade.
One of the other caveats I found is that when using only the outer or inner portion of the edge, always observe where the unused part of the edge is . . .

Emil