I find that the most difficult part of growing Hoya praetorii is getting it established.  It is a bear to root, and to begin growing well.  I grow mine two ways; in semi-hydro using either hydroton, or Growstones, and in self watering pots.  It never wants to dry out, but also can’t stand to be sopping wet.  It also does far better the warmer that you can keep it.