I am following this forum for a couple of months now and I think I have an idea of the most techniques (not of all details, not the real big fishes with various fins or the wxyz-ALS rules). Sometimes I understand these too (after explanations), but I am almost never able to spot them by my own. All the same I solve most of the puzzles, even some of the really difficult ones. These are my "house-made" techniques which may be not very elegant but which give surprisingly often some useful eliminations.
1. Basic techniques (including [hidden] pairs and triples, blocked candidates, X-wing, Swordfish, coloring and xy-wing [often difficult to spot]), in short: as far as Simple Sudoku comes.
2. Beyond Simple Sudoku I look for Empty Rectangles (mostly already done by multi-coloring), AURs, xyz-wings, remote pairs or - eventually - a BUG pattern.
3. If these techniques don't solve the puzzle I look for contradictions. Generally I begin with a "promising pair" in a "base-cell". A promising pair is often a unique pair on the grid which contains one candidate of which there are only a few left (maybe only in two or three boxes) and one "power-candidate" (you find everywhere on the grid). If the first candidate in the base cell (for example "a") leads to an elimination of the other one ("b") in a cell which is seen by the base cell, you can eliminate this "b" (if the base cell contains a "b", it would be eliminated anyway).
4. If that does not lead to any elimination I try the (here so called) a-b-c technique. I choose a triple and look what happens if one of the candidates was not in the cell. If the cell contains "abc" and "ab" leads to "a" then "b" can be eliminated. (If the "right candidate" is "c", "b" cannot be correct either). This works often if the chosen cell leads to some eliminations due to an AUR.
5. If that does not work I give up.
Some will argue this is pure "trial and error" (which would not bother me very much), but I don't see any really substantial difference to the nice loop and ALS techniques for instance. In my opinion any (advanced or not advanced) technique works on the principle that you exclude candidates by imagening how the grid could be filled. Example: a finned X-wing only works because you can make the following deduction: If the fin-candidate is wrong you can eliminate the candidate in the same box (by the X-wing rule). If the fin cell is right the same elimination can be done, because the fin cell contains "the" candidate and is in the same box. I don't believe in the fundamental distinction between "seeing a pattern"(good) or "observing cause and effect" (bad).
Thanks for your attention