If you don't have a developed rootzone yet, for example you just started a seed or put a small rooted plant into a larger pot (transplanted) then you will want to water until the medium your growing in is moist, not soaked, and then not water again until it's almost dry.
I really like this analogy. You will get a feel for how much water they need by just tipping the pot with your hand or gently lifting the edge of it. Also just visual observation light colored soil/coco will usually be dry and darker color will be moist/wet.