Gorgeous flowers, I love them! Hoyas grow so fast, but I haven't quite got the hang of getting mine to flower yet.
I'm afraid our only secret with regard to Hoyas is that we forget about them and sometimes forget to water them. Every summer they go outside for fresh air and to deal with the mealies which are attracted to them no matter what you do. Or so it seems. And then, every year, reminded perhaps by that drop of sticky nectar on the chair we were going to sit in, we are wowed again by the flowers.