I always liked the "save often" method of doing the Serpent Temple.
I would explore for a bit and every time I had an encounter and came out of it unpoisoned, I saved! If I got poisoned, I reloaded the game. As a result, I didn't need to carry around too many cure poison potions and was able to save the ones I did carry for the encounter with the NAGA, etc.
Worked well.