New York - Subway

Notice the trash box within the station

It is not easy to navigate New York subway even for experienced travelers. Its complex network of train is one of the most challenging ones I have seen. More difficult than Guangzhou, German, Singapore, Malaysia train network. Just look at the Subway map and one will understand why.

There are a few considerations for travelling in New York subway (from my limited 4 days experience in New York). It needs a lot of logical thinking and common sense:-

(1) Direction - Uptown v. Downtown. Sometimes the signage will just show Brooklyn or Queens and traveler must know the map of New York well to know the position of the end point against the train station one is heading.
(2) Express v. Local stops - Certain train station will have local and express train service and hopping on a local train may extend the travelling time. For example A, C, E lines may indicate different express or local line even though they may be heading to the same direction. How to differentiate? It is through the subway map, the train station signage and announcement made by train operator. This is the most challenging aspect of travelling on the subway.
(3) Exit location - Train stations may have many exits and getting on to the right exit needs experience. For example, 23rd Street/ Court Square has exit on 23rd Street and 21st street. Distance between exit can be 1 km apart. I ended at the wrong exit on the first day to the hotel and had to walk. Fortunately I have iPhone Map to guide.
(4) Different subway line within the same station - Going to the right one requires examination of signage. Especially important if traveler wants to change subway line. It may involve finding the right platform (which can be the same one or a different one).
(5) Train may be taken off the line as and when announcement is made by the operator. Traveler has to listen to the announcement which is typically in American slang. The other indication is when everyone gets off the train.

Apart from that, train can get delayed because of technical issues. I had the experience of slow train on the E line. 

In addition, there are strange people asking for money in the train.