Wet Tissues, Bangkok
Toiletries and Medical Supplies: Wet tissues are a good bet in this hot and humid city. The pollution is rather bad due to the amount of traffic and the vehicles' emission. Just imagine the smoke and dust settling on your sweaty skin... You can also wear a face mask on the streets.
A nice big cotton hat to keep the scorching sun off your cute nose and loose cotton clothing. No lycra or jeans you'll regret it.
Toiletries and Medical Supplies: Carry a family pack size of tissues everywhere for the occassional mopping of brow and hands. You will regret it if you don't. Also a bottle of water to keep yourself watered throughout the day.
Miscellaneous: Deodorant with a capital D. Ladies I suggest you use a man's brand to keep you nice and fresh, the women's brand are pants.