Everyone is different, there is no "one-size-fits-all" method but I can recommend a few important factors for you to consider. 1) A structured method to follow is far more effective than learning a bit here and a bit there. 2) If you want to speak with Thai people, you should learn with Thai people. 3) Consider arranging private classes with an experienced teacher to get your questions answered clearly & accurately. Private classes may cost more, but you will learn faster and get more out of your time with less invest in the long run, and it's much more fun too!