First, always buy property that you can afford.  Before you buy the home you will need money for a down payment and money to cover the monthly mortgage payments as well.  You also need to be ready at all times to cover any difference between what the renters pay and what the monthly mortgage payment is.  You also need to take insurance premiums and upkeep into consideration.  Make sure that you can pay all of these costs even if the property sits empty for some time with no renters.

Next, make sure to find properties that are in a good location.  Beachfront locations are highly sought after and will usually fill up with tenants, but if you find a property that is in a town without a developed tourist industry, you may find it incredibly difficult to rent your home out even with a great location.

Finally, make sure that you take the best mortgage that you can find for your property.  Talk to several lenders before you commit to anything.  Mortgages are generally taken out for thirty years, so even small changes in interest rates can add up to a lot of money over that amount of time.