routes - - Having multiple routes into a city will make your airline-owned hotel more profitable. - I agree that maxing passengers is the best way to go. With passengers at 100%, add planes, then routes, then flights until you your ticket sales dip.... then find a nice balance. - routes from one continent to another are most profitable, of course.
ADs: - the higher your ad budget, the more likely your ad is to succeed. - always advertise, its worth the failed risk. - Double your benefit by advertising a route into a city where you own a hotel - If successful profits of both go up.
misc: - invest in charters wisely, just like the stock market. - If you invested in a charter, don't overlap it's routes or its value goes down. - if a competitor heavily invests in a charter, quickly open a route to compete with it, fly only two flights or so and undersell it to cause the charter value to nosedive. If will cost you $, but its comical. - open a hotel where you have any hub. - if a hotel you just built sucks, advertise it. If the ad fails, sell it and rebuild.