Do I need to buy my plane ticket before applying for a Thai Tourist Visa?

Hi there,

I am new to the page and I would like some advice;

I am a UK citizen applying for a Thai Tourist Visa (maximum stay: 60 days).

I was wondering if I needed to buy my plane ticket before I apply for my visa or should I wait to hear if my visa is accepted before purchasing ??

And I roughly know the documents I must provide as evidence, but is there anything major I must include with my evidence ??

Any advice would be greatly appreciated,

Thank you for taking the time to read.