Quick Tip #1:
I have known some great fly tiers. One in particular was a perfectionist. He would not use a fly unless it was perfect. One tip he gave me was not to use scissors to cut the thread as it would leave a small tag which could be seen. Instead he used a straight blade of some sort such as an X-acto knife for a clean cut. (This is NOT the tip yet.) So I got an X-acto knife and used it for years. One day I was tying and I reached for some material. As I did something began to roll off my desk. I closed my legs to catch it, and I did. Unfortunately it was the X-acto knife. Four stitches later I was as good as new and a little wiser. Since then I have switched to a cuticle remover to cut thread. It works perfectly and is SAFE.
Quick Tip #2:
When showing a friend how to tie some parachutes dry flies, he was having a very difficult time splaying the tail fibers and keeping them splayed. A very simple fix is to use a loop of thread (or any other small diameter material) at the bend of the hook. Pull it from bend through the tail fibers to split them. To split the tail in half, run the thread evenly between the fibers. Then tie down the excess thread and you have a perfectly split tail.
Please note there are 3 tail fibers in this example. When you go to split 3 fibers, you pull the thread such that your loop straggles the center fiber.