You're standing on the banks of a clear, calm pond. The grass has given way to dirt and mud beneath your bare feet, and you casually pick up a jagged grey rock and throw it into the water. What happens?
The surface of the water is disturbed. Rippling waves run out from the point of impact in an ever-widening ring. But what happens after that?
The water is still once more.
The same principle applies to the work that must be done as an indie publisher, if one wishes to have any success. It's not enough to make one announcement, have one promo, or join a group of your peers. That one gesture will make a ripple, but the effect will dissipate quickly. If you wish to keep the waters from growing placid once more, you're gonna need a lot of rocks.