Hello! It's great to hear about your planned trip to Vietnam. I have compiled some useful tips for you.

Best Time to Visit:
The best time to visit places in Vietnam, such as Hanoi, Nha Trang, Phu Quoc, and Ho Chi Minh City is from November to April as the weather is typically warm and dry during these months.

Route and Accessibility:
International flights land at Hanoi and Ho Chi Minh City. From there, domestic flights, trains, and buses connect to Nha Trang and Phú Quốc. In-city transportation includes taxis, motorcycles, cyclos, and on foot.

Accommodation and Booking:
Consider booking accommodations in advance. There are a variety of options, from luxury hotels to budget hostels. Websites like Booking.com, Agoda, and Airbnb can be useful for making reservations.

Clothing and Essentials:
Pack lightweight and breathable clothes for the tropical weather. Rain gear is advisable as unexpected showers can happen. Also, don’t forget to pack sunscreen, hats, mosquito repellent, and your international adapter for charging your electronic devices.

Health and Safety:
Stay hydrated at all times. Avoid drinking tap water and stick to bottled ones. Use mosquito repellent to protect against mosquito-borne diseases. It is also recommended to have travel insurance for any unexpected medical emergencies.

Local Etiquette and Respect:
Vietnamese people are respectful and expect the same in return. Dress conservatively particularly when visiting religious or historic sites. It's also considered respectful to ask for permission before taking photos of people.