I'm not sure if it's different with other people, but with me at least there is a big difference to facial-hair, hairs and head-hair, hairs :p I shaved up until the coarse facial hair is remove, being very careful to go no further and retain the nice fine wispy head-hair

I've been having laser and IPL for ages now, with most of my dark facial hair gone (just the annoying blonde stuff left

), this technique allows the lase tech to zap the facial hair right up to the facial/head transition zone

It should hopefully be quite easy to tell where your facial hair finishes and your head hair starts (there will prob be a bit of a mixed zone, but that's ok, just shave that and get rid of all traces of facial hair being the important bit), just feel for the difference in thickness of hair and texture, and make sure to take your time. I found once you establish the boundary, its easy to maintain if you push your wispy head hair up out of the way, it seems it much easier for the razor to shave the short, coarse facial hair compared to the long soft facial hair

Well that's how it worked for me at least. Good luck!