Investment properties need to be close to public transport. It is no good having an investment property in a location with no access to public transport as it is isolated and harder to lease as it appeals only to a small fraction of people.
Areas close to a transport hub are generally more attractive for tenants, but this does mean that due to their popularity they can be expensive and can be located in high rise apartment buildings.
Sometimes one or two stops off this transport hub are the better buys, providing there is still infrastructure which is easily accessible.
Public transport is the go to choice for many people as it is the cheaper alternative to purchasing a car, especially these days with car sharing and hire a car for a day websites there is no need for the car all the time so public transport is the go too choice to get to work.
Look at the main hubs for where offices are concentrated, ie business sectors then reverse engineer the best ways to get there from different suburbs. Then work out the suburbs you want to purchase in, and you have narrowed the areas done considerably, which will help you locate the ideal location for your property.