This simple phrase "flip a switch" refers to doing something so easy that it doesn't require much effort at all. It’s like saying "it’s so easy just do it". Here's an example:
Flip a switch and just watch how more and more people will be interested your product.
That's a simple example of how the phrase can be used to convince a reader to do simple task (the specific task is irrelevant). What would be a good translation in Spanish. I more direct approach but less interesting could be:
Asi de facil ....
but is there any kind of idiom that expresses this idea better.