In our judgment the first two most important things for orchids to thrive are:
1. Being correctly potted (see cultural guide).
2. Watering them properly.
Water only on sunny days, before noon.
So that any water that fell on or in between leaves has a chance to evaporate before sunset. Your plants will fare much better if you delay watering by a day or two or even three rather than watering them on a cloudy, humid or rainy day because on such days the air is already saturated with water vapor and water that fell or splashed on or in between leaves will not, under such weather conditions, evaporate before sunset.
Water your plants with room temperature or lukewarm water.
Wipe out any water that splashed on or between leaves.