Hrm… I’m generally against guides since they tend to be too generic and everyone needs to adapt them to their own needs, but there is one for MILD that is quite good. In short, you need to be specific in your mantra. Give your mind clear signals and it will help immensely. Anyway, here are two guides that really will help get this concept down.
Forming a Relationship with your Subconscious
And its follow up article
I am a Lucid Dreamer: Commanding the Subconscious Mind
Hope those help 