This is a contentious issue in WILDing. Many guides talk about 'flashes of colour' (for our purposes hypnagogic phosphenes Phosphene - Wikipedia, the free encyclopedia). I've only had a couple of successful WILDs, but in my attempts it's been a long time since I had just blobs of colour, often now I will experience flashes of an images, scenes, sometimes even a low-grade 'dreamlet' in my mind's eye; I've experienced music, voices, tactile sensations, all without ever entering SP.

The way I see it I've trained myself to be conscious of the hypnagogia I never used to notice. So as often as you can lay down and try to access your hypnagogic state, it's like coming out of a pitch dark room into sunlight, at first you can't see a thing, over time things become clearer and clearer.
After a while you'll find that you can interact with your mind's eye images somewhat and your own visualisations will become more lifelike. It takes a lot of time and a lot of practice to master visualisation/ hypnagogic imagery, and I still haven't cracked it, which is probably why the 'mind awake/body asleep' approach, in which the only aim is to 'reach SP', is generally favoured. But I think that by observing and coming to understand the dream formation process you make a stronger basis for WILDing because you really understand how it works if you know what I mean.

So attempt as often as you feel comfortable with and aim to get into deeper and deeper states of hypnagogia while still lucidly aware. These are some pretty nice guides on V-WILD http://www.dreamviews.com/f12/how-vi...ctively-40861/, http://www.dreamviews.com/f79/mancon...ml#post1849737.