At the beginning of a game, you should transport goods between industries. Passenger and mail transport are only profitable if you build large networks. Most money you can earn with coal or oil transports. You should not use ships at the beginning of a game, because ships are very expensive.
There are industries that only produce goods if you deliver certain goods. If you try to collect planks from a sawmill that is not delivered with wood you will not earn any money.
See also: Car industry-Tutorial
If you spend more money as you have, you will go bankrupt after 3 months. Do not build or buy expensive things until you have enough money. Removing tunnels is very expensive. Building a lot of big rail stations is also very expensive. You can start Simutrans in freeplay mode to switch of the bankrupt check.