The default airport is Shenzhen Bao'an Int'l Airport (SZX).
Creating routes to and from this city with 747-8 to large cities such as London, Seoul, Tokyo, Los Angeles, etc. can get full occupancy and high profits. It's often recommended to start here as the city has decent ratings, but most players prefer nearby airports Hong Kong or Guangzhou. However, the city may attract moderate to heavy competition but can usually sustain it. Its locaton is advantegous for connecting to many major cities in China, India, etc.
Shenzhen Bao'an Int'l Airport will usually achieve maximum slot usage, but this will happen late in the game (the early 2000's). As a result, the airport may be a good purchase at this late point in the game. Additional airports are not recommended as they will rarely achieve a status beyond level 2 or 3.
On routes to medium-sized cities, planes such as the Boeing 757 and Airbus A340 are preferred. On routes to other large cities, planes such as the aforementioned 747, the Airbus A380, and the McDonnell Douglas MD-11 are best used. Small planes should not be used as they will not meet the demand on the route well.