How do your characters survive? Presumably by working so what do they do? What products are made in your world? How are others persuaded to buy them? Are there things your world does not allow to be made or sold and if so what and why? Is there a black market (there usually is!)?
Also how do your characters find out what is going on? Can they tell what is truth and what is propaganda? Are adverts truthful? Are there governing bodies regulating these things? Or is your society a simpler, barter based one?
Talking of adverts, I will just share a flash fiction story of mine, The Art Critic, which is now up on Cafelit. Do check out the website for some fabulous stories by a whole range of authors. I'm delighted to have work on here. Hope you like the story.