I am really enjoying this game. Something I found out is that if you spam click the parts tab in the factory, for some reason you gain blood rapidly. It's been nice to have lol
A good strategy: once you get fuel and buy the crane upgrade, glide close to the bottom without using your engine (spacebar) and use only the arrowkeys sparingly. Bounce off of the windmills and use the boost from the cranes and gold stars. This will allow you to travel farther and earn more money. The mystery upgrade can help by allowing you to bounce and roll farther but is not worth buying right away. Instead, save up for better plane designs, lightweights, and aerodynamics.