Don’t over-water your plant or let it sit in water, as this can cause root rot. Signs of overwatering are yellowing leaves and the stems drooping over. Drain away excess water and reduce your watering.
You don’t need to mist your Zamioculcas, it’s happy in drier conditions and normal household humidity should be fine.
Don’t rush to repot your zamio, they don’t like to have their roots disturbed. As they are slow growers, they are unlikely to need to be repotted more than every 2 years. They also have a very strong root system compared to other plants so a slightly misshapen pot is common and not a problem for the plant.