What is easiest? Sell me things that I already want but don't know about, or changing my interests and then convince me to buy a particular product? Incidental

What is easiest? Sell me things that I already want but don't know about, or changing my interests and then convince me to buy a particular product? Incidentally 5 years after moving into an apartment I still need a good curtain for the kitchen. If I see an ad for a place I can upload measurements and get the results sent to me I would be very happy to pay.