Choose flight ticket
Because my plan is only 5 days so I take full advantage of time. On my first day in Bangkok I will go straight to Pattaya, then arrive in Bangkok and come back Vietnam. If you choose to stay in Bangkok before being Pattaya, you will have to carry the goods. Bangkok will have many things at market or supermarket, shopping center mall that you want to buy. The ticket should be booked in the morning and the return ticket should put in the evening. You take advantage of two more days.
Bring a pen to your trip
When you board the plane, people will have to fill in the immigration badge. If you do not bring a pen, it will be difficult to borrow. When the plane landed, you have to look for the pen to fill in the new information that is a very time consuming.
Must use Klook
This apps is very useful for booking tickets or coupons in Thailand including purchasing sim. I put 4G SIM card through Klook discount code, so only pay 25.000VND instead of 300 bath (near 210.000VND) buy directly at sim card counter in airport. Besides, you can buy BTS tickets daily and visit Floating Market, sex show Tiffany... to will also be given a lot of price incentives.
Shongthaew
If your schedule hang out in Pattaya, learn about Song Theo, which is similar to Bangkok's Tuk Tuk but much cheaper. This type of car usually runs at the center of Pattaya, the main direction is to walking street, you just get on the car, do not ask the price and check the place you need on the google map, if the car goes in the other direction press down the car and find other cars in the same direction you want. Each car takes 10bath/person. If you intend to go further than the center, give the address to the driver and pay the price down to half.