There is very little difference between subliminal persuasion and covert persuasion. Both involve the non-obvious things that we can do to persuade someone to another viewpoint or even to the point to action (i.e.buying)
The list of possibilities is large.
We can influence covertly by who we are.
We can influence by what we wear.
We can influence by what we do.
We can influence by how we say what we say.
We can influence by structuring our sentences using covert hypnotic suggestions (presuppositions)
We can influence by contoling the mood of our prospect using anchoring.
We can influence by making sure the setting of the meeting is conducive to communicating.
I offer sales coaching on such things,
The article below is about such things.