Before buying any property, the first question any potential buyer must ask is the reason for the purchase. Are you planning on buying as your primary residence, a holiday home or as an investment? In each case, the thought process that you need to go through will be quite different.
If you are buying purely as an investment, it is important to “think with your head and not with your heart”. Rather than basing your purchasing decision upon what you personally would like to buy, you need to clear your mind and focus purely upon the numbers, as in many cases the best investment properties could very well be something completely different from the type of property you would choose personally.

One of the first decisions an investor must make is an “exit strategy”
as this will have a major effect upon deciding what type of property to buy.
Someone who is planning on keeping a property indefinitely and is purchasing primarily for receiving a regular income will have a different strategy from someone who is looking to make a quick return by “flipping” a property _ for example, buying a property at an early stage and then selling either during the construction process or shortly after completion.
You’ve probably heard the old cliche “that the three most important factors to consider when purchasing property are “location, location and location”. Cliche or not, this is still very true, as it is the element that will have the greatest effect on the returns on your investment.
Put yourself in the shoes of the person who you expect to rent the property or buy it from you when you decide it is time to sell. Which factors are going to be of most importance to them? If you are buying in Bangkok, then some of the most important factors to consider are how prestigious the area is, ease of access to transport to the inner city, closeness to shopping malls and other entertainment areas.
If you are buying in Pattaya, then the most important factors will be how close to the best beaches the development is, proximity to the city centre and whether there are sea views from the units.
via Tips for property investors | Bangkok Post: business.