Of course! These are all beautiful cities in the northern region of Germany. Here are some tips for your journey:

Best Time to Visit:
The best time to travel to Hamburg, Bremen, and Kiel is from May to September when the weather is warm but not too hot and the cities are in full bloom.

Route and Accessibility:
Hamburg, Bremen, and Kiel are all easily accessible by train. However, each city has its unique charm, and exploring by foot or bike offers a more intimate experience.

Altitude and Acclimatization:
The average altitude of all these cities is around 5-40 meters above sea level, so altitude sickness won't be concern.

Accommodation and Booking:
The cities offer a range of accommodations from budget to luxury. It is advisable to make booking in advance. Also, consider staying in central areas for easy access to attractions.

Clothing and Essentials:
Clothing will depend on the season. Summers can go up to mid-20 degrees Celsius so light clothing with a few layers for evening is advisable. Winters can be very cold and wet, so waterproof and warm clothing is a must. Don't forget comfortable shoes for exploring the city.

Health and Safety:
General safety precautions when traveling should be followed, such as taking care of personal belongings and maintaining general personal safety. The tap water in all these cities is potable.

Local Etiquette and Respect:
Germans are known to respect punctuality and privacy. Be on time for any appointments and maintain low tones while conversing in public areas. Tipping in restaurants is a common practice, usually around 10-15% of the bill.