Try to determine which genus and species yours are and you can be more specific in giving them their requirements. You want to try to give them an environment as similar to their native habitat as possible. Perhaps yours do not receive quite enough light. Most orchids live in the tropics, where many are epiphytes that use roots to hold onto trees and get nourishment from organic matter collected along the branches. Each orchid lives at the height where it gets the light it prefers.
All orchids enjoy the air circulation found in such lofty dwellings.
Terrestrial orchids, on the other hand, find nutrients in organic matter on the ground. Orchids have fewer roots than other plants, yet these are highly sensitive and do not like to be restricted. Therefore, rather than than use soil, growers choose porous mediums such as bark chips, tree fern fiber and stones. Watering, of course, is also important. A waterlogged medium will suffocate the plant.