What should I include in the letter to myself for the DTV visa application and how should I handle my flight booking?

I just returned from HCMC with an approved DTV. I am a self-employed freelancer. I am the sole director of an Australian company that I channel my contracts through. I wrote a letter on my company letterhead stating that I am the sole director of the company, described the nature of my work, stated that my income is entirely foreign-sourced with no work undertaken for Thai companies, and that all of my contracts are remote/home-based. I also described the contracts I have completed in the last 6 months in the same letter (clients, nature of work, dollar value). Accompanying the letter, I had a copy of the company registration and a letter from my accountant in Australia confirming that I am in fact the soled director of this company. I also attached all of the contracts from the last 6 months and my professional portfolio. This is just for the confirmation of employment - there were more documents submitted for the financial section. Happy to answer any further questions.

You don't apply at a Thai embassy directly, you do it online.

None of this makes coherent sense. Just apply online using the website. Select Ho Chi Minh embassy

Guys I know who have UK Ltd company had applied in the UK but did write the letter to themselves. It was on company headed paper and basically it was from themselves as Company Director saying they could work remotely, specifically from Thailand. The supporting documents were the company documents showing the were the Owners/Directors.