Flying in a day before usually gives you more choices of flights, more leeway to find deals, etc. If you fly in day of, then you are limited to flights that arrive before a specific time (remember you must be checked in and onboard the ship no later than 60 minutes before sailaway, some lines it's even 90 minutes), reducing your opportunity to look for deals. Many people are able to find less expensive flights+hotel combinations than flying in day of, so keep searching for deals.

If you must fly in day of (sometimes you have to), here are some good guidelines:

1. Make your planned arrival at port no later than 4 hours before departure - this gives you leeway for delays with flight, baggage, and transport from airport to port. So count back, departure at 5 for example means onboard at 1pm. If airport is 30 minutes away from port (for example MIA to Port of Miami), then that's back to 12:30. Depending on the airport give yourself 30 minutes to an hour (for MIA at least an hour), to get off the plane, collect bags, and get ground transportation, so that's back to 11:30. So you're back to a flight that must arrive no later than 11:30 (flying into MIA sailing from Port of Miami).

2. A non-stop is typically better than a connection. The more flights, the more opportunities for delays, lost bags, etc. Notice I said typically because:

3. The earlier the arrival the better. Gives you more room to work if something goes wrong. A connecting flight that gets you in at 9am and has several later alternates (on the same airline) if something goes wrong, might be better than the non-stop that doesn't get there until noon, depending on your situation.

4. Be aware of typical weather when choosing your flight route. In winter beware of snowstorms in northern airports, but in the spring/summer DFW, ORD, ATL, etc can be nightmares for thunderstorms for example.

5. Know your options if you miss sailaway. Do you have a passport so you can fly and join the cruise at an intermediate point? Is the first stop the next day or 3 days away where you've missed half the cruise if you join it at that point? Are there obstacles preventing you joining the ship at the first stop? For example, many lines have stops at private islands (frequently the first stop) that don't have airports. Another example is a cruise from Miami that has a first stop in Key West. You would think you could just drive down and join the ship in Key West, but unfortunately there is a law (PVSA) that prevents that. How would you pay to join the cruise at the next point - travel insurance, credit card etc? Know the day of cruise contact number for your cruiseline.