Is it better to fly or take buses?

Buses are cheap but time-consuming. Only fly for legs longer than 20 hours, such as crossing from northern Peru to southern Chile.

Do I need to book accommodation in advance?

Only for high season (December-February in Patagonia) or major festivals like Carnival in Rio. Otherwise, book 24-48 hours ahead.

How to plan a 6-month South America route

Focus on a 'U-shaped' path starting in Colombia and ending in Argentina to follow the seasons. Dedicate 2-3 weeks per country to avoid burnout and keep your transport budget manageable.

Follow the weather. Start in northern South America (Colombia/Ecuador) between January and March. Move south into Peru and Bolivia by April/May, and reach Patagonia between October and December for the best hiking weather.
Use the 'U' route. Fly into Bogota. Travel overland through Ecuador, Peru, Bolivia, and Chile. Cross into Argentina and finish your trip in Buenos Aires to fly home.
Choose your pace. Six months allows for 8-10 major stops. Do not attempt to see all 12 countries. Pick two regions—e.g., the Andes and the Atlantic coast—and stick to them to reduce long-haul bus fatigue.
Build in buffer weeks. Schedule one 'do nothing' week for every 4 weeks of travel. You will get sick or experience transit delays; account for this by not booking every single day in advance.

Is it better to fly or take buses?: Buses are cheap but time-consuming. Only fly for legs longer than 20 hours, such as crossing from northern Peru to southern Chile.
Do I need to book accommodation in advance?: Only for high season (December-February in Patagonia) or major festivals like Carnival in Rio. Otherwise, book 24-48 hours ahead.