Tips for starting IAD

So I just recently just begin Washington airport and currently at level 11. I was wondering what is a good way to earn money quick.

Is having a lot of small regional aircraft a good strategy or should I try get planes like B737 or A32X?

Please help.

If you know someone who plays this game, actively try to form online contracts with them. The contract rewards can be a huge boost in XP and silver planes, allowing you to quickly upgrade your airport. Whenever a new airport is released, I also use this method to form contracts with people around me and develop it as quickly as possible. I don’t know if this is the right answer, but I’ll share my know-how. Enjoy the game.