Hi there! It's fantastic that you're planning a trip to Miami, Nassau, and Havana. I'd be happy to provide you with some travel tips.

Best Time to Visit:
For Miami, the best time to visit is between March and May due to pleasant weather. Nassau is delightful from November to April avoiding peak hurricane season. For Havana, November to April is ideal as it is the dry season.

Route and Accessibility:
You can start your journey from Miami, which has excellent air connectivity. From Miami, you can take flights to Nassau, and then from Nassau to Havana. Make sure to check visa requirements for each destination.

Accommodation and Booking:
All these spots have a broad range of accommodations to choose from. It's recommended to book your hotels in advance, especially in peak season. Airbnb is a popular option in these cities.

Clothing and Essentials:
Pack light, breathable clothes, swimwear, sun hats, and sunscreen. Comfortable walking shoes for city tours, and smart casuals for nightlife are recommended. Also, don't forget your beach essentials.

Health and Safety:
Ensure you're updated on routine vaccines. Pack a basic first-aid kit. Stay hydrated and use sunblock especially in the hotter months. Miami and Nassau are generally safe but do take the usual precautions against pickpocketing in Havana.

Local Etiquette and Respect:
Miami and Nassau have a relaxed beach culture. In Havana, being punctual is not strictly adhered to. Always respectful to local customs and traditions. Try a few words in Spanish, the locals appreciate it.