A Phuket purchase runs through a predictable sequence: shortlist, viewing, offer, reservation, due diligence, contract, transfer. What varies is how much of the work happens before the reservation deposit rather than after it.
Before you reserve
Establish the ownership structure being offered and confirm it matches what you are willing to hold. A villa marketed as 'foreign freehold' is usually freehold of the building with a lease or company holding over the land — a materially different proposition from a condominium unit inside the foreign quota.
Ask what the reservation deposit does. In most Phuket transactions it takes the property off the market for a defined period while due diligence runs, and the terms on which it is refundable are the terms that matter.
Due diligence
Title search, encumbrance check, building permit and access rights are the minimum. On villa purchases, confirm that the land title permits residential construction and that the access road is either public or covered by a registered servitude.
For units, confirm the foreign quota position of the specific unit — not of the building in general — and obtain the juristic person's outstanding-charges statement.
Transfer
Transfer happens at the Land Office. Transfer fees, specific business tax and withholding tax are negotiable between the parties in practice, so agree who bears which before the contract is signed rather than on the day.