Outer: Strike a physical position that the icon holds and wear clothes, etc that they do. Invoke and feel the position you have placed yourself in be an empty vessel for that deity, eventually visualizing yourself as the deity will be easy.
Inner: Meditate and see your body and surroundings dissolve in 5 colored light into emptiness. From that emptiness arises a single spark or drop of consiousness that is the diety. It radiates light in all directions that reflect back and make you into that diety. Perform an invocation to bind the visualized form with the actual form.
Secret: Perform acts that throw the body/mind into a state of ecstatic union while holding the visualization of yourself as that diety. Orgasm, Inner Heat, Illusory Body yoga, Dream Practice etc – these open the mind to your own innate clarity and divinity which need not be visualized or generated. This in turn melds with the constructed visualizations.
Innermost Secret: Recognize that you are inherently divine, and that things just as they are, without elaboration, are self-perfected.
Innermost Secret is not “better” than Outer or vice-versa. The best mode is dependent on need, application ,and ability.