Szia Istvan,
A lot of people are likely going to jump into this thread and remind you its ILLEGAL (that's true) and you are taking a huge risk of going to jail and paying an enormous amount of money to get out of jail (that is also true) ... we all know you are going to do it anyway.
With that said:
- understand how to read Thai IDs
- keep in mind some of the bar girls are underage and carry fake IDs
- boyfriends and jealous haters are going to come looking for you
- Never posses (in your room or person) anything pornographic.
- FTP your raw video and images to your server as soon as possible, before leaving
Thailand. Do not carry it with you.
Typically you can befriend one or two bar girls, and have them help recruit others for you. Don't film in the same place you live. Keep changing locations of where you are shooting.
I will let the others add their 2
and input on costs, etc.
Good luck!