The guy who played the shuttle pilot in Skin of Evil had the easiest job. Just lay there unconscious for the entire episode!
Tasha's demise was pretty mind blowing at the time. Main cast members just didn't get killed onscreen like that in those days. Mind you, she set a world record for security guards surviving in Trek up to that point. I would imagine Denise Crosby still beats herself up a bit over deciding to leave the show to this day.
It may have not been the best of episodes, but the ripples from it defined Data in some ways, (that he kept that hologram of Tasha was touching) and made for some interesting storylines later on.