Be very much aware of agencies in Bangkok. Some are good, while others are flagrant scams.
You may wish to read this:http://www.nittayo.org/agencies.html
One of the best job sites for Thailand is http://teflasia.com
, but again, beware, as occasionally some of the advertisers are agencies pretending to be schools. remember that the best jobs go to the people who are already in the country and available for an interview at a moment''s notice. Most mainstream schools will not be recruiting again until September/October in time for the next semester. High street language institutes, and there are literally dozens of these, will employ at any time: walk-in interview recommended.
Don't forget that you will need a degree to teach in Thailand and that preferably you should obtain a 12 month Non-Im visa B
before you arrive here, to avoid inconvenient trips to Thai consulates in neighbouring countries.