If you were going to stay for 6+ months then my advice would be not to arrange anything permanent until you get here. Book into cheap hotel accommodation for the first week, buy a cheap mobile phone, rent a motorbike and drive around the areas you would like to live in, you will be amazed at how many small ‘house for rent’ signs you will see.
Broadly speaking there are two long-term paradigms to follow either as a long stay tourist by living in a tourist community or as a long stay local by living in a Thai community. Living in a Thai community in an amazing experience because you will find all your needs taken care of on your doorstep. You will find all manner of businesses being run from your Thai neighbors houses for example laundries, shops, bars, and restaurants. Many of my neighbors are BGs who I will see locally as a neighbor and socially as a BG; they pop in for falang boyfriend advice, for email advice and sometimes for the obvious. The local newspaper
http://www.phuketgazette.net/ has a good online selection of houses for rent but nothing beats driving around your favorite locales.