SINCE writing last week's column, I have received several queries from readers who own apartments and houses who wonder whether now is the right time to sell, particularly in the light of further price increases. If a property owner is going to sell, there are two main considerations: investment time horizon and alternatives. Another aspect is the familiar ''shall I buy or rent?'' question. If you own a property which you also occupy, this is a compelling reason for not selling. If you do sell and then rent accommodation, you are exposing yourself to potential future increases in rents which, in the long run, could cost you more than your mortgage repayments, particularly if you bought a few years ago. Then, the rule is not to sell simply to take profits. This brings in the time horizon. If you are looking to move abroad in the next year or two, for business or family reasons, then it may be appropriate to sell now. If there is a correction in the next two years, this may come at an inconvenient time for you, as you may not be able to get the price you would like, or, worse, you may not be able to complete the sale before you leave. If you move into rented accommodation now while yields are low, the rent will be affordable and you will be gone before the rent review comes up. If, however, you expect to stay in Hong Kong long term, let us say at least five years, then even if prices drop in the short term your mortgage costs are fixed and, by the time you want to sell, prices will almost certainly have recovered. Another good reason for selling is to move up or down in size. If you wish to upgrade by selling your small unit to buy a larger one, a strong market is as good a time as any, as long as you feel financially able to make the move without stretching your resources. However, in terms of downsizing, perhaps because your family is smaller and you no longer need a large apartment, you have to look at the wider issue of what you do with the equity released from the sale. An investment in Hong Kong residential property has done well over the past three years, with prices doubling in most areas. Looking ahead for the coming three years, it is hard to see this performance being repeated and it is worth looking at alternatives. The star performer this year is going to be the office sector. So look to buy a small office unit on the fringes of Central or Wan Chai. However, the smallest unit is usually more than 1,000 square feet and it is difficult to find a good one for less than $45,000 per sq. ft. This means you would be looking at a minimum investment of $5 million. If you preferresidential property, there are opportunities in the region. Bangkok is attractive as long as you confine your interest to prime units in the city centre or near the river where the transportation is good. Prices for good apartments are $1,500 to $2,000 per sq. ft. The Malaysian market is now good for long term buyers. Look to pay $1,000 to $1,500 per sq. ft. The Singapore market is expected to soften a little in 1994, following exceptional price rises in 1993. This presents an ideal buying opportunity, particularly at the top end where units are in short supply, at prices up to $4,000 per sq.f t. The Indonesian market is currently closed to foreign buyers, but the rules may change this year to permit foreign ownership of strata units. Should this happen, Indonesia is a large market with huge potential and it is well worth having a look.