What ive been doing is opening the good window in a city and checking if they have any good stuff, anything that would normally swing widly in price from city to city(spice,iron,velvet,oil... not food

)if a city has one of these i hit asses local prices (you need at least 1 point in trade I think) if the goods you saw in the trade window appear in the assess then makea caravan for that city with those goods.
Your going to need about 6-10k to start doing this mind you, but so far ive doubled my money on every trade, with one velvet trade costing me 10k for the caravan and selling for 78k
A quick edit, I noticed in my version(steam) the tax from expensive good was actually given to me rather than taken away so I made more money before i got a patent
