I use segment of my finger to mark distance from tip.
If I have overlay, I cut across top first then do one side at time, too lazy to mark.
Though! I think Eric's method is top of cool! I never thought of this, will need to try as it seems more consistent.
For bow with no overlay, just eyeball, any mess up is a character
![Grin ;D](http://www.primitivearcher.com/smf/Smileys/default/grin.gif)