There are some general requirements that apply to all staff employed on cruise ships. The age limits for employees is usually 21 to 65 years, although trainees might start at 16 years. You'll need a valid passport and a 'seagoing' visa for the country of the company you're going to work for.
Contracts range from three to ten months in length, although most are six months. These are usually renewable if the company is happy with your performance. You'll usually need to take a medical before the job offer is considered firm - you'll have to pay for this. While there's full health coverage on the ship, you're still advised to buy your own travel medical insurance.
If you're looking at a skilled job opening, then you'll need the relevant qualifications for that role - see below for more information.
As a person, you need to be highly motivated and energetic, being interested in taking on new challenges. As you'll be constantly living in close proximity with the people you work with, it's important that you are sociable and oriented towards teamwork. A hard working approach and strong self-discipline is needed, especially as long shifts might be required.
Apart from the port visits, you'll always have to abide by the ship's company rules, so you have to be willing to do that. At the same time, a degree of independence is needed, as you'll be a long way from your home base of friends and family for long periods of time.