We organize. Lenin literally wrote a manual outlining the basic general steps, and those were used successfully all around the world by the working class to take over the state. It is also a great way of fighting fascism.

We organize worker unions, then start using our power of collective bargaining and strikes to force them to concede more and more. All that while building a paralel socialist party and bottom up councils to direct the decisions, this party will eventually take over the state. In an ideal world this can be done nonviolently (it did initially happen peacefully in russia) but the elites will resist so we have to be prepared and strong enough. Along the way we may need to arm ourselves, save up on food and necessities to defend against the state violence that will come. For that we need a good chunk of the population onboard but its definetly possible. About half the people in most countries are already convinced voting can only bring the lesser evil so half the battle is done for us.

This is just one way, of course there are several schools of thought on the left about how to do it. Anarchists have an interesting idea of just building the all institutions we need parallel to the state too, although their method never worked on a large countrywide scale, it works pretty well for smaller communes.