Your next move becomes stronger when nobody knows whether you even intend to move.

Uncertainty about whether you will act is itself a form of position. When people cannot tell what you intend, they have to prepare for several possibilities and cannot arrange things around you, which is exactly what predictability gives away. This is not manipulation; it is simply not announcing. Most people announce out of a need for reaction rather than any strategic reason.

Before telling people what you are going to do, ask what the telling accomplishes. If it is only anticipation or approval, keep it. Then act, and let the move be the first anyone hears of it.