Allow adequate time between flights. One hour is generally the minimum necessary to allow for the possibility of a delayed arrival, to make your way from one gate to the other, and to have your checked luggage transferred between planes. Some airports require greater margins even for domestic flights, and more if the journey involves an international connection. Be wary of signing up for routings that involve tighter connections.

This is even more important these days, when fuller planes make it harder for airlines to put passengers who miss their connections onto later flights. Airlines are not required to hold planes for incoming passengers on delayed flights, although they do so on occasion.

Consider the size of the airport when accepting minimal connection times. At big hubs, airlines do not necessarily assign arrival and departure gates based on the convenience of connecting passengers.

Check out your flight's on-time performance history. Some flights almost always arrive late, and airlines are required to provide statistics on late arrivals.

Understand the difference between "direct" and "nonstop." Flights listed as "direct" will make stops en route but will continue with the same flight number. During severe travel disruptions, even direct flights can have a portion of the route canceled.

Avoid flights during peak travel hours, and seek out those that depart early in the day. Flight delays tend to get worse as the day goes on. Flights that start the day at an airport are listed as "originators" and are less likely to be delayed since they don't depend on a plane to arrive from another location.