Hoya is a genus of 200-300 species that are native to parts of Indonesia, Thailand, Vietnam, India, Malaysia and other Asian countries and parts of Australia.
For a happy Hoya you'll need to be able to provide consistent temperatures above 60F. For this reason, Hoya make excellent house plants as most homes are not kept below this temperature. For optimal growth, temperatures of 70F or higher are required. Humidity requirements vary, but most Hoya will do just fine in house hold humidity of 30% or higher, though once again, they will thrive in higher humidity (50%+ is ideal).
Water requirements vary, see each individual Hoya product page for the specific care for that particular Hoya. In general, Hoya can be left to dry out a bit before watering again. If your Hoya starts to yellow then it's likely been overwatered. If the leaves begin to turn thin and are easily bent into a "U" shape, then it's been underwatered.