One of the best things about Joomla is being able to make a living from it. Developing an extension, whether it's a component, plugin, module or even a template, will allow you to generate income and at the same time contribute back to the community.
There are many user group sessions where experienced extension developers in the Australian Joomla! community will guide you through the process of developing an extension, submitting it to the extension directory and various business models to make money from Joomla!