The best way to go about looking for and making arrangements for a Bangkok to Khaoyai taxi would be through the Internet so make it a point to look for the right websites that would facilitate your requirements for you.
There are different types of taxi services that you could arrange in Bangkok whether you would like to travel within Bangkok itself or whether you would like to make use of a taxi service to move from Bangkok to khaoyai as well as back to Bangkok.
Taxi services in Bangkok in particular can offer you a variety of services as well as packages so you will want to decide whether you would like to make use of different taxis for different trips or whether you would like to book one that you could use throughout your trip.
It is recommended that you speak with people that have been to Bangkok before as well as people who may have travelled from Bangkok to Khaoyai through taxis so you can get an idea on how much it is going to cost you in general as well as how much time it is going to take you to get there.
This would allow you to plan your trip accordingly as this would help you to make the most out of it all instead of trying to figure things out when you are already out there. Get a list of websites that will assist you with information on travelling from Bangkok to khaoyai as well as try looking for forums where you could interact with others who may be traveling to Bangkok so you can exchange ideas.