Alright to most this isn't really the key to the universe but to stitchers everywhere it is damn near close. That ever elusive French Knot. No other stitch can send even some of the most seasoned stitchers running in fear. I have to admit that I only recently figured out this stitch (and I've been stitching for 30+ years).
When I was a new stitcher looking at the instructions that came with the new kit I was working on a french knot looked easy; I mean you just wrap the thread around the needle and pull, right?! I mean what is so hard about that? Then that darn little knot (if it even formed a knot) pulls right through to the back of the fabric..........(insert swear words here and getting the "look" from your mom). Due to that experience I avoided french knots for years; 28 to be exact. Meanwhile my sister had mastered the french knot, even the colonial knot (learning candlewicking will help you with that).
So now that you know a little of my history with the knot, let's get to those keys.
The first key is tension. You need to keep a firm tension on the thread, if you are starting a new strand you need to keep tension on the thread tail on the back as well. Also don't release the tension until right before the stitch is finished. And stop pulling on the thread the moment you feel the knot "pull back". Don't yank on your thread.
The second key is thread length. Don't work with too much of your thread. I only use a couple of inches near the fabric. You should use enough to get two to three wraps around your needle and have enough to easily insert the needle back into the fabric.
The third key is speed. You can't speed through this stitch. When pulling through to make the knot you need to pull with a steady even speed. Not to fast, not to slow, steady.
The fourth key is placement. I know, I know the instructions tell you to go back down into the same hole you came up in. Well they lied to you! My best knots have happened when I went down just a little bit away from where I came up. On Evenweave this is just the next hole over, on Aida you may have to split the threads.
The fifth and final key is practice. I'm serious. Practice. Grab that scrap piece of fabric, thread a needle and get started.
I hope these keys will help you master this stitch.
Happy stitches and keep those needles moving!