Those puzzles gave me a lot of trouble too.Maybe it was just because it was late and I was tired and/or feeling sick, but I hit a point in The Witness where a lot of the tutorial tetris-block puzzles were throwing maaaaajor roadblocks at me. I'd looked up a few hints online for a few puzzles I'd been stumpedon here and there. But for the tetronimo ones, I was looking up how the puzzle concept was even meant to work in the first place, and still having trouble. Part of the problem was that I thought I'd been doing what the puzzle wanted me to do already, but was wrong somehow, but was close enough that I'm not sure what I'd been doing wrong. And then there was one with a 4-square of subtraction blocks in a single space (third puzzle), and even looking up the solution outright and staring at it with my pencil and paper scratch in front of me, I just couldn't grasp how it was supposed to work - I assumed the subtraction had to be in that 4-pattern, but could not for the life of me figure out how to get that final shape with a solid 4-square to subtract from it. Ugh. Anyway, I've made some decent progress(?), I have 3 lasers going right now, I think the monastery area was my favorite so far.
It was giving me really bad motion sickness but I cranked the field of view way up high and turned on the reticle and it got better.
My first piece of advice is that when you feel stuck,you should just go somewhere else. Almost always the issue is that you've gotten stuck in a rut of thinking of the puzzles in a certain way, and what you need is to go to a different location, solve different puzzles and come back with fresh eyes.
The second piece of advice, for the tetrominoes specifically, is they actual physical pieces and play a around with them. It makes it much easier to experiment and see how they fit together. I just cut a bunch of pieces out of paper when I was in that section.