General: There are over 500 different varieties of known hoya! Whoa!
Light: Most hoya prefer medium to bright indirect light. If the light is too intense the leaves may fade.
Water: Allow the soil to completely dry between waterings. Consider how much light the plant is receiving - water more in the spring and summer and allow soil to be drier in the winter.
Other Notes: Remember - plants need both sun and water to create energy - without enough light the water may sit in the soil and create root rot!