Bill,

I sometimes 'crimp' the line. It ll depends on how big the hook eye is and what size tippet the fly will use.

If I have plenty of room, I don't bother with the crimp.

If I'm afraid it will be 'tight', then I first trap the guard line with a couple of thread wraps, pull it out in front of the eye, crimp it with a pair of heavy needle nosed pliers, then draw it back into position, fold it back, trim it, and tie it off. What you want to do is 'flatten' the line as much as you can, and this takes a serious set of pliers to do well.

Buddy