Learning Tetris and the Questions I have

[WristTendenitis]

Hello, I'm really bad at tetris, 36 lines/2mins for t spinnning. I'm trying to learn t spinning and if there are any helpful tips on how to build better when I first start the t spin double factory, please let me know.

Also, I can see that you guys are posting visual guides of tetris; I want to try manipulating tetrominoes without the time limit or the given order. I just want to freely try out combinations. I could do paper cutouts but that seemed like a lot of work. How can I use the simulator that you guys are using? Thanks.

[WristTendenitis]

Also, do you guys keep count of open pixels that you have to fill up? At any point during stacking?