What is the best marketing strategy that you used to make the product a success?

Hey indie hackers,

I created a startup with some of my friends and we did multiple steps to get started. First, we did some polls to validate the business viability. Second, we created an app to do some user testing to get some feedback. Now, we made a website to be able to market the product.

Here is my question :

What is the best marketing strategy that you used to make the product a success?

Thank you for your time!