My spoken Thai is very basic... I learn a lot better when I learn the writing system first. I am in no position to teach you how to speak. I can give you some advice about writing though.
If you don't know how to write Thai, try copying Thai letters. Strokes begin from the small circle (contained in most of the letters). Took me awhile to figure out. The materials for learning Thai I've seen aren't nearly as good as what is available for Chinese.
In regards to the subject of this thread...
I have a book called "Vocabulary of Chinese" that is intended for Thai people to learn Chinese. The vocabulary is not very up-to-date. However, it does have a phonetics section. It tries to map 4 of the Thai tones to the 4 Mandarin tones. It maps the Thai low tone to the Chinese dipping tone.
I had some Thai people I knew read the Thai equivalents of different pinyin given in the book, and it just did not sound correct. It sounded like Chinese, but it sounded like it could have been a different dialect.
I personally find it easier to understand Chinese spoken without tones than Chinese spoken with Thai tones, but I am not sure what an actual Chinese person would find easier to understand.