+1 with aoitsuki. You will learn that bankrupcies are common, and not to be ashamed of. That it is possible to profitably run a company based in Nauru flying only Pilatus. That you can have 10 130-seaters competing on a 250 potential line. That some companies make money with 100% russian steel flying material. That it takes years to get an A320. That leaving a good line unoccupied is a call to opponents to fill it. That having a full filling of a line does not deter some opponent to fill them anyways. That price wars are more costly to the attacker than to the defender(doesn't mean they are useless, but use with extreme caution). That the big guys often fly unexpected planes. That the 4th group penalty is manageable...up to a point. That a missed plane transition can kill your company. That sometimes you are lucky & all your opponents die, and sometimes, everyone jumps on your best lines, leaving them in ruins. That the game is unfair - opponents are the ones who set up the difficulty, not Sami. That A148E on 2200NM routes when fuel prices are at 1500$ are not that much a good idea. That a company flying 4 hours a day can make 20%+ margin. And that's it's not a good idea to try to do the same.
This, plus thousands of other things, BW won't teach you. Come learn with the best(not me, I speak about GW3's big boys, Jumbo, Hoek, Bingo, and the others). Look at their setups. How their fleet is structured. How their schedules are structured. How they plan their fleet replacements. The statistics screen is a huge tool to see the best in each category, and then to look at him for gathering data. Look to the best in terms of LF, and see how wekk they perform(most of them, not very well, but they are exceptions). Look at the best in plane use, and see if they perform well(better than average, but it's a much weaker predicator than expected). Look at companies with few fleet groups, companies with many, see how quick they develop...and how quick they die. Looking at their stats, their flights, their announcements, is a mine of information on how to reach objectives.
And then, set up your objectives : be the more profitable now or later? Grab as much space as possible? Have a steady income? Make your main base a stronghold, or spread out to avoid attacks? Lease or buy when you get settled(in the beginning, leasing is a no-brainer)? Lower prices to annoy opponents or rise them up to improve profits? All those questions have no definitive answer, just you have to decide what is the most fun way to play for you.
I've got already 6 bases, but with no more than 25% market share on each(bar the very special London City). It's maybe not the best way to play, but it suits my style. It's a strategic choice. And I never, ever bankrupted(it's my second GW3, and I'm well established). But others with other strategies make better than me. Find your own style, but do it in a real environment. In beginner/intermediate games, you'll take bad habits.
And if you fail, be sure to analyze why. And "why" is never "it's unfair". The game is unfair(no more slots at Heathrow, hehehe), and other players are going to attack you, but their attacks will succeed only if you make mistakes. And you will make. Be honest enough with yourself to say "I was wrong", and you'll be good soon.