Which city to target?

I'm ready to sell with Bob Ross's method.

18 spots in one card, now I need to decide which city to target.
I have a city of around 23k people, so around 10k households, which is the number of postcards sent out, and this is great for this small city, it's also a decent economy city.
One problem with this city is that there are a limited amounts of businesses. So I could run out of them if I don't make enough sales to complete the card.

While in a big city, even if I call 100 businesses and only get one sale, I wouldn't run out of them. Though, in a big city, 10k postcards aren't a great value like they would in a city that have exactly 10k households.

I'm not really new to selling but I'm not yet experienced enough, yes I have studied a lot of stuff about sales in the last year but I also need experience and rejections, so a small city could bury my chances of success. While in a big city I would never run out of people to call but I have less value to offer..

I thought I could jump high and do more than 10k postcards sent out in a big city, so I have more value to offer, but that's another ball game since I would need to raises my prices by a lot.