Basically, there are only about 10 elements that you need to learn to do anything, with the most straightforward being a diagonal line running in the main direction of your twill background. That one is really easy, while other things that are twisting things away from that straightforward thing are, hm, let's call it "more demanding". There are ways to do curves, and horizontal and vertical lines, and diagonals running opposite to the current twill direction, and they aren't that hard - but the challenges grow when you are doing multiple things at once and have to keep track of all of them (plus decide on the fly how the pattern should move on).
Also not helpful at all? Having a little reference sheet to help keep track of how the tablets should stand, and then discovering, after a long while of wondering why things occasionally go totally pear-shaped with no good reason whatsoever, that there was a lovely little mistake in that reference sheet. Bah. Duh. I did about a gazillion facepalms in my mind when I found out what had brought me down there again and again. (I had mostly looked at the bits left and right of the erroneous point, which were a-ok and really helpful, and only occasionally referred to the faulty part.)
So. Current status?
I have made a tree-like thing.
As you can clearly see, I'm still working on merging lines. I'm also still working on a lot of other things, such as starting diamond shapes out of nowhere in a timely fashion. Things are progressing, though, albeit slowly.
There is also still that occasional problem to keep left and right apart. It's getting better, though - having told myself so, so often by now that "towards the weft, slants up and left" that it starts to seep into the backbrain.
Next up: More new and exciting design elements - such as horizontal lines. Yay!