The first step is to compare different VCO topologies, for e.g. LC VCO (NMOS only, Complementary etc), Colpitts VCO, Ring VCO and so on...based on the pros and cons of each architecture and your preferrence...choose one of them and start the analyses and simulation...
In cadence, you have to run DC and transient simulation first to see whether the oscillator starts or not....next you need to run PSS and PNoise simulation to get a more exact oscillation frequency and phase noise estimate....
i hope this helps...also search the forum..there have been some similar questions already asked and answered....!!
Regards