Understand the market you want to invest in. This means reading property related articles, looking at growth trends for areas you are interested in , use the internet and also talking to experts. At a minimum you will need to gain an understanding of rental yields for the area you want to invest in and also form an expectation regarding future property prices.
It may also make sense to use the services of a buyers’ agent. They can provide expert advice regarding expected returns, rental yields and what is a fair and reasonable property price.