Things to avoid when treating a zombie village

Avoid curing the zombie villager next to any mob that assaults villagers, including illagers and zombies. When a zombie villager is cured, these mobs may not attack the zombie villager first, but they do so afterward. Don’t heal a zombie villager during a raid, for instance. Read more how to cure a zombie villager

Zombie villagers

Because zombie villagers constantly attack iron golems and iron golems attack zombie villagers even when they are being treated, it can be beneficial to temporarily remove your iron golems from the town. Bring the iron golems back once the zombie villager has been cured since without them patrolling the paths, zombies might decimate your community.

If the zombie villager accidentally assaults you, make your tamed wolves sit down because they will attack the zombie villager as well till it perishes.
Avoid using a power or flame-enchanted bow on a zombie villager if you want to use an arrow with a weakness tip to give it the weakness effect. If you do, the zombie villager could be instantly killed or burnt to death.

The weakness effect is not imparted upon the zombie villager by punching it with a weakness arrow.
Since you don’t want to hurt the zombie villager while healing, use a shield to block zombie villager strikes more safely.
When curing, try not to let your zombie villager infect any additional villagers. read more how to cure a zombie villager