is better to underwater than overwater a Hoya. Their thick leaves store water so only water when the soil gets fully dry. They do not like their toes to stay wet so make sure you have a fast draining soil (plenty of perlite and sand) and a pot with a drainage hole. These can be epiphytic, like orchids, so they do not need nor want wet soil. Heart Hoyas prefer bright indirect light or a sunny window sill.