Sure! Here are some travel tips for your visit to Marstal, Faaborg, and Copenhagen in Denmark:

Best Time to Visit:
The best time to visit these Danish cities is during the late spring or summer (May through August), when the weather is warm, and all tourist attractions are open.

Route and Accessibility:
Fly into Copenhagen's Kastrup Airport (CPH), which is well connected to international and domestic flights. Faaborg and Marstal can be accessed by road or ferry. Copenhagen has an efficient transportation system that includes metros, buses, and boats.

Altitude and Acclimatization:
The altitude in Denmark is quite low, close to sea level, so no specific acclimatization is necessary. If you're traveling from a high altitude location, though, you may feel some minor changes.

Accommodation and Booking:
Each of these cities offers a range of accommodations from budget to luxury. It is recommended to book in advance, especially during the peak tourism season.

Clothing and Essentials:
In summer, bring lightweight clothes, but always include a jacket or sweater, as the weather can change. If you're visiting in spring or autumn, pack warmer clothing. Rain gear is helpful any time of year. Comfortable shoes are a must as these cities are best explored on foot.

Health and Safety:
Pharmacies are widely available if you need over-the-counter medications. Tap water is safe to drink in Denmark. Follow local guidance regarding COVID-19 protocols.

Local Etiquette and Respect:
Danes value punctuality and respect for personal space. It's also considerate to learn a few words in Danish, although most residents speak English. When visiting any churches or historic sites, be respectful of the surroundings.

Remember, Copenhagen is a cycle-friendly city, so cycling could be a good option to get around and explore. Walking tours are also a great way to immerse yourself in these beautiful Danish cities. Enjoy your trip!