Keep the light and water levels consistent per the type of orchid you have, since there are so many varieties there can be quite a range. Keep the plant away from drafts though, such as from leaky windows or vents, which can shock the plant.
I have a dendorbium orchid, I repotted it this past Spring. The last leaf has turned yellow but there is a ton of new growth on the stalk. The other is in a similar condition except the growth has started at the bast of the plant. I am almost scared to water them as they seem to yellow and/or die at a much quicker rate!