What is the procedure to work in Thailand?

It's best to secure a job before arrival. Otherwise marry a Thai and start a business

There are very limited work opportunities in Thailand for foreigners..

And you need an employer to sponsor you to get a work permit even for the very limited opportunities available to legally live and work in Thailand..

If you are a good English language speaker and especially if have some teaching experience then that's one of the very few job opportunities that are available in schools as an English language teacher.

There are others in highy skilled IT or management jobs for foreign companies in Thailand but you need the have experience and relative skills of course for those.

Salaries are generally low except perhaps for very specialized skills and jobs..

Good luck but you will struggle to find anything at all.

Why would you want to, terrible salaries and poor employment contracts.

You need to find a Thai employer interested in employing you. They will then apply for a work permit.

Following that you apply for a work visa.

There are many jobs restricted to Thai nationals only, so make yourself aware of these.

But it's only certain jobs foreigners are allowed to do,so understand that as well

Good luck

1) find a job in Thailand

2) your employer gives you paperwork to apply for non-B work visa

3) your employer applies for your work permit

4) you get your non-B visa and wait for the work permit to be issued

5) start working