In the past I had been learning new words and small phrases from my wife as we speak a mix of Thai and English at home. That has worked well for me to be able to get by asking for basic things and kidding around with people. Also that taught me the basics of proper pronunciation.
Now lately I've become more interested in learning the language more thoroughly. I've just started learning the alphabet, a few letters at a time and getting the sounds/understandings down through my wife. Its been a mix of the Benjawan Poomsan Becker book Thai for Beginners and
Thai-Language.com for reference.
I think most of the difficulty for people comes from a lack of desire to learn. I think with a set of weekly lessons or a classroom setting it really could be a piece of cake. Especially if one used it on a daily basis at home or something as well.