I tie off on the post with different thread, just like flyandtie, because I found that after a few fish - sometimes just one - the fish's teeth sometimes broke the exposed hackle stem running from the post to the eye and the hackle would unwind from the post. I also think tying off on the post looks cleaner, although I'm sure the fish don't care. Check out this tutorial on Hans' website of the Klinkhamer Special and tying off on the post, just as flyandtie described it. Pictures with it may make it easier to understand.

http://www.danica.com/flytier/hklinken/ ... pecial.htm

Joe