Decoupling questions

Hi,

I'm designing a circuit currently for a uni project and have been asked to calculate component values - especially decoupling capacitors. I haven't found much info on how to calculate specific values but as my circuit is connected to mains, i assume using a 1-100uF capacitor would be wise.

It is a RF circuit center frequency of 30kHz with an oscillator onboard so I'm assuming I'll need separate decoupling for this component. How do i calculate what value i should roughly use?

Thanks