Of course! Here are some travel tips for your visit to Gongju, Buyeo, Iksan in South Korea:

Best Time to Visit:
The best periods to visit for mild weather suitable for exploring are the spring (April to June) and fall (September to November) months. Also, the cherry blossoms in spring and colorful foliage in the fall provide beautiful scenery.

Route and Accessibility:
You can reach all three cities relatively easily as they are all well-connected by intercity buses and trains from Seoul. The KTX train service is the fastest.

Altitude and Acclimatization:
Altitude is not a problem as these cities are all at relatively low altitudes.

Accommodation and Booking:
It's recommended to book your accommodation in advance. The region has several guesthouses and hotels of all price ranges. There are also historic Hanok stays available for a traditional experience.

Clothing and Essentials:
Pack according to the season. If you are visiting in winter, ensure to carry heavy woolens as South Korea can get quite cold. During the summer, wear light clothing but carry a jacket or sweater as indoor places blast air conditioning.

Health and Safety:
Carry basic medicines and a first-aid kit. If you have any specific medications, make sure to bring them as well.

Local Etiquette and Respect:
Koreans generally prefer subtlety over extravagant behavior. Dress modestly while visiting temples and historic places. Respect local customs and traditions, especially in rural areas. The cities you're visiting have a rich history, especially in the Baekje Historical Areas, so respecting monument rules is appreciated.

Remember to learn some Korean phrases. Even though English is taught in schools, not everyone you encounter will be fluent in it.