There used to be a nice list of songs with links to lessons etc. Has that been taken offline on purpose or just a mistake? What was particularly nice was that the songs were arranged in order of increasing difficulty.
An order of difficulty can help learners to plan, since they can have a look at the list and select their most sensible next targets. If I already know A, then C should be easy enough to tackle next, instead of B which may be too far ahead, and so on.
We could have a similar list about techniques/refinements. Of course this could be highly personal? A shared list would be some kind of an average impression.
What I’ve tried so far -
Sukui - kinda no-brainer, issue seems to be just making it clean&sharp
Hajiki - fairly easy to pull off, one needs to just learn the right touch to make a decent sound. It’s a nifty technique, like it so much I often do it when jamming/improvising
Suberi - recently started to learn this. Can fail with the 1st and 2nd string so usually do it the slow and clumsy way rather than fast and wrong 
Uchi - have a hard time wrapping my head around this. The sound seems quite weak when I do this.
Suri (slide) - very versatile, actually a family of techniques since it’s used for different situations/purposes and styles. Easy to do as a focused technique, have been playing around with it; takes a lot of practice to make exact and clean - also hard to fully combine with playing (same as keshi)
Keshi (dampening/silencing strings) - just tried it a bit. Haven’t even bothered with it, there’s enough stuff to think of when playing already…
Do you have very different experiences?