Sure, traveling to Sydney, Brisbane, and Cairns can be an amazing experience with their rich cultural heritage, beautiful cityscape and landscapes.

Best Time to Visit:
The best time to visit these Australian cities depends on what you're looking to do. Generally, September to November and March to May are considered the best times as the weather is pleasant and tourist crowds are smaller.

Route and Accessibility:
All three cities are well-connected by air with international airports. You can also use railways and roadways. Inside the cities, public transportation like buses, trams, and ferries are easily available.

Altitude and Acclimatization:
All three cities are at sea level, so you won't have to worry about altitude sickness. However, do give yourself time to acclimatize to the time difference, especially if you've traveled from a faraway country.

Accommodation and Booking:
There are several accommodation options ranging from hostels to five-star hotels. Book in advance, especially if you're traveling during peak tourist season. Also, you might find some unique stays on rental platforms such as Airbnb.

Clothing and Essentials:
Pack according to the season. Summers can get quite hot so light, breathable clothing is recommended while winters require warm clothing. Don't forget your swimsuit, sunscreen, and a good pair of walking shoes as there's lots to explore on foot.

Health and Safety:
Australia is relatively safe, but standard precautions apply. Keep your belongings secure, stay hydrated, and ensure you have travel insurance for any health emergencies. If you decide to swim, be aware of currents and marine life.

Local Etiquette and Respect:
Australians are known for their laid-back and friendly nature. Respect local traditions and customs, keep the environment clean, and remember to tip for good service as it's common in Australia.

Enjoy your trip! It's sure to be an exciting adventure.