You will see gorgeous pictures which depict life as experienced on that particular line.  The first thing you'll notice is whether the style of dress is formal or casual, and the representative ages of the passengers.  This will be important if you are traveling with children or prefer to travel with your own age group.  The cruise line will emphasize its strongest features and most popular activities, and tell you about their dining and gaming facilities.  You may prefer a small, intimate ship for quiet relaxation, or a larger one with a greater variety of activities and dining facilities.