A recent article in The Daily Telegraph called What to pack for Thailand came up with the following list:
1. A good rucksack
2. Insect repellent
3. Sunblock
4. A money belt
5. Walking shoes
6. Sandals
7. Lightweight shirts and trousers
8. A light scarf (sarong)
9. Lightweight towel
10. Antibacterial wipes
11. Hair conditioner
Our list would be:
1. A good rucksack (daypack)
2. Insect repellent (especially during rain season)
3. Sunblock
4. A money belt
5. Walking shoes
6. Flip flops aka slippers
7. Lightweight shirts and trousers
8. A light scarf (sarong)
9. Lightweight towel (big)
10. Microfibre towel (small) (very useful to protect your neck from sunburn)
11. Small foldable umbrella (especially during rain season)
12. Rain poncho (especially during rain season)
13. MP3 player (if you are a music lover)
14. Blue tooth speaker (if you are a music lover)
15. International driving licence
16. Credit card (as a backup for a debit card failure)
17. Buff multifunctional scarf
18. A piece of rope
19. Duct tape
20. Instant glue (If duct tape fails to do your emergency repair)
21. Travel guide (Lonely Planet, rough guide etc.)
22. 3 way electric plug (2 extra sockets for charging your electronic devices)
23. Camera tripod (better pictures and selfies with self-timer)
24. Rubber wash bowl or bucket (if you want to do an emergency hand wash of your clothes)
25. Ear plugs (when staying in a hostel)
26. Portable luggage scale aka travel scale (If you like to buy tons of souvenirs or cheap clothing)
27. Flight bag; a thin sleeve that you put around your backpack or suitcase that act as a protective waterproof layer to catch dirt. Luggage handling is often under high time pressure and done very rough and disrespectful.
7-Eleven and other shops
A lot of items like ear plugs, scotch tape, instant glue, shaving foam, small washing powder, toothbrush etc. are also for sale at the 7-Eleven or Mini Mart stores. They are literally located on almost every street corner in Thailand. Flip flops, light weight trousers, light weight T-shirts and a small folding umbrella can also be bought at shops and street vendor stalls on the roadside. Often for much lower prices (100 – 200 bath) then in visitors their home counties. Be aware of a poor quality. When buying flip flops it’s wise to buy instant super glue at the 7-Eleven. Usually they are glued together with water based glue that will dissolve after getting wet again. In case of a plastic disposable rain poncho it is best to look for a big western size made from a slightly thicker plastic back home. The disposable rain poncho’s sold in Thailand are usually from a poor thin quality and too small to cover a tall western person.
Some other ideas about what to pack and what not can be found in this blog from Thailandredcat.com: Your Backpack for Traveling in Thailand.
Thailand Travel Base 