Is it cheaper to fly between countries?

Only if you book 4-6 weeks in advance on budget airlines like AirAsia. Once you factor in baggage fees and airport transfers, buses are almost always the budget winner.

Should I negotiate taxi fares?

Always use a meter or an app. If a driver refuses the meter, walk away immediately. Pre-negotiated prices are almost always double the standard rate.

How to save money on transportation while backpacking Southeast Asia

Stick to overnight buses and trains to save on accommodation costs, and use local transport apps like Grab instead of hailing street taxis. Avoid domestic flights whenever possible, as booking them last-minute or with heavy luggage fees destroys your daily budget.

Prioritize 'Sleeper' transport. Book overnight buses or trains for long distances. A 10-hour sleeper bus from Bangkok to Chiang Mai or Ho Chi Minh City to Da Nang costs roughly $15–$25, effectively acting as your hotel room for the night. Always check 12Go.asia to compare prices.
Master local city transit. Avoid airport taxis and 'tourist' shuttles. Use public buses or Songthaews (shared pick-up trucks) in Thailand, or the metro systems in Bangkok and KL. If you must use a car, use the Grab app; it provides a fixed price so you don't have to negotiate or get scammed.
Rent a scooter only if you have a permit. Renting a scooter costs $5–$8 per day and saves on daily taxi costs. Only do this if you have a valid motorcycle license and an International Driving Permit (IDP). If you crash, insurance won't cover you without these, costing you thousands.
Use slow boats for border crossings. When moving between Laos and Thailand, take the two-day slow boat instead of a flight. It is slower but significantly cheaper ($30–$40 total) and offers an authentic experience that saves you two nights of hostel fees.

Is it cheaper to fly between countries?: Only if you book 4-6 weeks in advance on budget airlines like AirAsia. Once you factor in baggage fees and airport transfers, buses are almost always the budget winner.
Should I negotiate taxi fares?: Always use a meter or an app. If a driver refuses the meter, walk away immediately. Pre-negotiated prices are almost always double the standard rate.