Very simple. Get a job first (find an employer who will employ you). Then they'll do the paperwork for you. But unless you have a profession that a Thai person cant replace you, you will have close to zero chance unfortunately
Right, so what's the whole idea of 'Tax return'?? Why do you need to provide that if they don't care whether you have income or not? Easy to just throw answers that are not true. Don't mislead people