Your new Hoya plant should be planted in well-draining soil.
When you first pot your hoya, wait a day or two, and then place the pot in a shallow dish of water. Leave it there until the top soil is damp. This saturates the soil and gives the plant a good drink. Watering from the bottom up will avoid damaging the newly planted roots.
Water again only when the top soil gets dry to the touch.
Provide humidity
Hoya get a lot of moisture from the air, so it's a good idea to provide some extra humidity for your Hoya plant between each watering.
You can mist them every couple of days if you are not in an already humid environment. It is better to mist the hoya and wait until the top soil is dry to the touch, than to risk overwatering the plant.