If you are regretting starting off in the area that you began in for one reason or another (maybe the airports are too far apart, etc), you can completely up and leave that area and start over in a new area without having to delete the app. Here’s how to do it.
First, make sure that you have a good amount of Bux around. An average of 1.5 bux for every 1 plane that you have should be sufficient. Then, go put all of your airplanes into the hangar. You will need the Bux in order to place the planes back into your airports later.
Next, close out every single one of your airports. You’ll get back a substantial amount of coins for each airport you close, which you will need to keep this going. Finally, go to whatever part of the world you want to set up shop in, and start opening airports there. After you open as many airports as you can, start adding your planes back in.
Where you should open up shop depends on what you want to do. If you want to have very short flights so that you always have something to do, open up in the middle of Europe. If you want a substantial wealth of cheap airports that will allow you to pocket a ton of coins, then open up in Australia, or (to a lesser degree) the southern half of Africa. If you are looking for a large number of giant airports to accommodate lots of huge aircraft, open up in eastern China or in India.
If you get bored and all of your planes are in the air, tap the airplane icon (two to the left of the menu) and tap on one of your flights to watch the plane fly. Coins will fly by for you to tap, but every so often, a giant coin will fly by, which is worth 10 coins. Between 2 and 5 giant coins appear per minute, depending on your luck. Every once in awhile, a Bux will appear, too.