I've been on 50 cruises. Here are 5 things I wish I'd known before sailing in the Mediterranean.

Many cruise lines, like Virgin, Celebrity, and Disney, start the Mediterranean season in early spring and sail through early fall.

Going early or late in the season usually means you'll have more tolerable weather and smaller crowds in some of the big destinations like Athens.

I made the mistake of going on my Mediterranean cruise at the end of May (over Memorial Day weekend).

Some ports of call, like Nice, France, were easy to get around, but others like Rome were packed to the gills. I wanted the day to end before we even made it to the Vatican on our tour.

My biggest tip for any cruise — but especially for Americans traveling to Europe for a Mediterranean cruise — is to arrive at your embarkation city at least a day before your sailing starts.

This gives you plenty of time to ensure you make it to the port, especially with the airline delays that typically spike in the summer. The boat isn't going to wait for you if you don't land on time

Even though it means paying for lodging and likely a few meals before boarding the boat, getting a good night's sleep before a jam-packed vacation is worth it to me.

As a bonus, arriving early also gives you a chance to explore the city.

Some of the major European tourist destinations have strict dress codes — typically everyone must at least cover their shoulders and knees out of respect.

If you're planning on checking out Vatican City in Italy or the Meteora monasteries in Greece, be sure to pack at least one outfit that fits the bill.

Most cruise ships have laundry services (self-serve or valet), so you can wear the same dress-code-approved outfit for a few excursion days if needed.

If you're looking for a unique excursion that still gives you the highlights of a European city, I recommend booking a food tour. I've done tours in places like Amsterdam, Budapest, and Paris, and I've never been disappointed.

Food tours can be booked through third-party travel operators, like TripAdvisor or Viator, and offer the chance to see some of the major landmarks of a city, try local dishes, and learn some history all in one outing.

The tours are usually led by locals, which means the guides can also give you some good recommendations if you have time before you need to return to the ship.

Mediterranean cruises can last anywhere from seven days to two weeks, depending on the company and itinerary. Booking every excursion through the cruise line can add up, but luckily, there are typically more affordable options through third-party companies.

But I only book with third-party operators if the ship docks right at the city I want to explore because I never want to miss the all-aboard time.

For example, on my Mediterranean cruise last summer, the ship anchored at Cannes, and I was able to keep my eye on it throughout my excursion.

If the ship docks in a secondary location and you have to travel to the big tourist destinations, I always book excursions through the cruise line. For instance, the day my family and I explored Rome, the ship docked in Civitavecchia, Italy, and we had to take a two-hour bus ride into the city.

Booking with the cruise company guarantees your return to the ship, even if your excursion runs late.