First and Foremost ... Understand the Financial Implications
Financial viability is a crucial aspect and one cannot ignore it. It is very important to ensure that one can manage that pinch of the down-payment and the EMI and the impact thereof on other key financial goals. In most cases there are cost over runs and hence careful planning is required. Try and ascertain the overall cost so that there are no surprises later - registration, furnishing, legal costs, broker fees, etc. If you are constructing a house, keep a buffer over and above the estimate that you get. As an investment, buying land would be preferred route, especially if affordability is an issue.
A key reason for investing in real estate today is the tax savings that it offers. While we look at the tax benefit that one gets, we forget that we would be losing the HRA benefit. Hence the tax benefit is lower than what is anticipated. If this is a second residential property investment, then there are aspects which need closer focus, such as the likely rental yield. Real Estate, as an investment has to be evaluated on the grounds of the capital appreciation that it would offer in the medium term.