For tspinning opponent:
With slower opponents, i try not to do too many b2bs (its pretty easy to start doing a lot with slower opponents), cuz i just get them all sent back to me, often comboed back in bits, giving me terrible garbage.
With faster opponents, i like to build high enough for a tspin and a tetris, wait for first b2b to come in, and then launch an attack. Send whatever i had built, and combo/tetris back the rest.
Tetrising opponents:
as long as they aren't too fast (< 15 tpm differential), tspins help me survive and sometimes beat them. but usually their b2bs give u nice 4-5 rows high single-column gaps to spin over, or combo back, while they are busy building for tetrises!
Against 3 widers, i try to do PC opening.
If i can't get a PC, i just close the PC gap, so I have 1 column in the middle of matrix for a tetris, and then build and do tspins over that middle gap. This way i find that i can survive 12-13 combo easy, but any more than that and its trouble.
if someone starts building 3w in the middle of a game, i concentrate on doing as many tspins as possible while downstacking (Normally, I would just downstack hoping to get nice mini combos)
idk how good these strategies are, i am a mediocre player at best. so u should probably try them, and see what works for you
