The game is not really hard... Although I apparently used a little different strategy - I first enlisted 100 scientists and sold almost all of my company. Then I got a contract on airships (150 workers) and that was more than enough to cover the research expenses. In almost no time I hade better airships... and then better. And even more... I also produced the Z-3 as fast as possible for myself, because Z-1 really s... doesn't pay well
This way, I could get anywhere in a fast and realiable way. And just got another contracts... And - don't forget the advertising... even the 15k can help you a lot in the beginning (it will actually cover all your costs on fuel and repair) And, I got rich revenues on those trade routes, though they are not nearly as efficient as your promo-ships. But a 10-ship fleet could get me around 5M per week (don't remember the type, sorry... I bet with Z-7s it would be three times as big...). The capacity/price thingy on the routes is rather strange as well, you have to keep an eye on the revenues, else you'll one day find out, that all of your routes are not profiting.