Moving to Phuket from Australia

Hello Jaset,
today I feel very talkative on Expat.com, so you are lucky.
You want to move to Phuket with your family, so I guess you have children. How many and what age? They might need to go to school, so I suggest you to find a place with an international school nearby. Anyway, if you are coming with business intention, than I suggest you first to find a good Lawyer and Consultant to set up your company. As you know you need a Thai partner who owns 51% of the shares. Second, as you are Australian I suggest Kata Beach or Karon as location for your guesthouse. Australian come often during low season here for the surf series and they important and busy hubs for it. High season kata and karon are packed too. 
although it might seem easy to start a business here, there are many things to consider and money is not a small issue.
In example if you want to invest 100.000 AUD, be sure to have additional 100.000 AUD as backup. For existing guesthouse and hotels, or bars and cafe, you will be asket to pay a key money to get into it, plus the cost of the activity, plus the monthly rent. Check the existing contract and for how many years is valid. Moreover make a little research on the area you are looking at for future development plans. I suggest you to spend at least 3 months without doing anything, just searching and listening around..