Tips... here is two:
See pic from my airline. Note that I open up the first marketing campaign even before getting any planes, first day. This is because the marketing price will go up as the airline becomes more complex (more routes, more planes, more staff) but stays anchored to the initial price.
Also, on the first day I increase manually the number of Corporate communications staff to obtain as fast as possible "Efficiency of your staff is currently: 103 %". You may need to have 2 or 3 staff too many in the initial game months to get 103%, and then just leave staff hiring on automatic.