i've read many things that u CANNOT have a one way ticket and enter thailand. simply, they will not let u in. and especially if u don't have a working visa, etc. u have to make sure... and if you want a definite answer, i recommend you calling a thai embassy around your area. if you don't know one visit their website.
http://www2.thaiembdc.org/
u should buy a 2 way ticket, but the 2nd trip be an open date. this is because, thailand doesn't want foreigners to enter into thailand and simply just "disappear" especially because thailand is one of the top destinations for highly wanted people to escape to... i.e. the canadian molester, the "suspected" murderer or bonet ramsey, etc.
anyways, goodluck on ur job and trip!
