Hi Jay,
If you are doubling the hackle , as Irvine says ,tie it in by the tip . Then , assuming that you are right handed , hold the butt end of the hackle between your thumb and index finger of your right hand , then use the thumb and index finger of your left hand to stroke the hackles backwards so that they mesh with each other. Wetting helps . Reverse the instructions if you are left handed. Do not pull too hard as the finer tip may break.
On the subject of small heads don't tie in the very fine tip but snip this off , make a V shaped end by stroking a few hackles forward and tie in this section in . You can gently pull through to minimise but make sure you have hold of enough to hackle to make it secure. Don't use lots of wraps ,you don't need them.
Alternatively , and depending on the pattern, you can strip one side of the hackle of its fibres and tie this in . Good for low water , low "profile" patterns.
Hope that makes sense and helps.
