Nice tutorial for beginners, not just for the teutons, but any other faction. Although the teutons are indeed very difficult for any fresh character.
I would add to the opening businesses part, that I open businesses as money comes along, that way, my income keeps growing steadily. Also I prefer businesses, where no menial delivery duties are involved. You mentioned cheap iron in Poland, Paris, etc. Those cities also happen to be poor in tool manufacturing, so why not open the business there? You don't need to taxi resources and you still get the 600 denar income. I always look for cheap raw materials in the goods market when deciding what business to open, as it usually turns good profit. Central and Western Europe mostly needs ironworks, the Eastern needs tannery, in my experience. Be careful opening dyeworks, as most of the time it promises 1000+ income, but you need the raw materials to do so. If there are no such materials [dyes, silk] present in the city by default, you probably don't want to open the business. I did that in Elbing, and instead of 1000 profit, it ran on barely 40 income, or even a deficit: there were no caravans, probably, where it could buy materials. Open dyeworks if there are no other business in the city offering real profit [500+]. If you happen to raid caravans or villages, stock the raw materials in your businesses, it turns a real profit, as acquiring them cost you nothing, contrary to buying and stocking, which don't show up in the budget report.
One more important thing! To raise quickly money, you might want to visit the Lithuanian cities with a couple of grands. In the beginning of the game they might not be at war [to me, war happened later]. One of the cities offer spices for 500-600. [which is crazy, and historically inaccurate, but you might want to take advantage of this probably early stage flaw] You can't find another city that buys spices under 800,