Absolutely, I'd be happy to give you some travel tips for your upcoming visit to Seoul, Asan, and Busan in South Korea.

Best Time to Visit:
The optimal time to travel to Korea is in autumn (September to November) and spring (April to June). During these months, the weather is pleasant and several festivals tend to take place.

Route and Accessibility:
From Seoul, you can easily reach Asan and Busan via the KTX (Korea Train Express). There are also bus services available.

Altitude and Acclimatization:
Seoul, Asan, and Busan are at moderate altitudes so altitude sickness is not typically an issue.

Accommodation and Booking:
There is a wide range of accommodations in these cities, from luxury hotels to budget guesthouses. Booking in advance is advisable, especially during peak travel seasons.

Clothing and Essentials:
For spring and fall, pack lightweight clothing with a few warmer items for layering at night. Rain gear may be needed due to occasional showers in these seasons. Winters can get very cold, so you will need warm clothing if you're visiting between December and February.

Health and Safety:
Korea is generally a safe country. Just follow standard travel safety precautions like not displaying valuable possessions in public and having the address and phone number of your embassy.

Local Etiquette and Respect:
Respect is highly valued in Korean society. Remember to bow when meeting new people. It would be beneficial if you can learn a few basic expressions in Korean.
When dining, wait for the eldest person at the table to eat first.

Remember Korean etiquette can differ significantly from Western cultures, so take the time to learn about them to ensure that you respect their culture. Enjoy your trip!