We present for the first time a detailed experimental study of the oscillation frequency, linewidth, RF spectrum and the phase noise of a radiation-pressure-driven micromechanical oscillator in a microtoroid geometry. Through this study we identify the critical parameters for optimal operation of this device and derive key expressions for tailoring the desired characteristics. The outcome of this study paves the ground for exploiting this unique phenomenon in photonic systems as well as fundamental studies in macroscopic quantum mechanics.