how do you sell stuff?

Don't talk like a sales rep, think "what would make me buy stuff from this person" and try to follow that. People usually don't like information overloads or technical talk even for extremely technical products, if they ask you question on it you can answer them with info ofcourse \o/
Make gib for Yawner 4: The Wild Snore if this helped 😼

I check with the local merchants for the cheapest items to sell for the highest prices and where,then I stock up on supplies and hire a few mercenaries as caravan guards to ensure I can get there safely. I might also procure some nonperishable foodstuffs if it will be a long journey, especially if traveling north into Nord territory. If the horse dealer is in a bargaining mood I might get another packhorse for the trip. I always make sure I've paid for whores and beer if morale is low before leaving the town.

disclaimer: i've never even done a yard sale
that said google would probably be better at finding customers than trying to cold call random people, I'm not sure what the tools are called since i've never done sales, but it seems like you could have google show ad's to people searching for "broken x", "how to repair x", "fixing x", "x repair", etc.
just be sure you don't give them a blank check, start off with x$ toward ads then put y% of the net profits back in to more ads if it works.
edit: you might have to make a web page and ad banner art
edit 2: market note, people are getting poorer and poorer as the value of money inflates away and minimum wage doesn't keep up, one way people save money is to cut space and move into smaller housing, and a primary way to cut space is to get rid of paper and books wherever possible, companies still print some stuff for local use or if it is their product (like putting designs on stuff), but for ordinary people printing seems like a diminishing market.