There are many visa options available to you. Much will depend, of course, on your long- term objective. Some visas, such as visitor visas from certain countries, are quite straight forward and can be granted electronically within a few minutes of application. However, if you want to cometo Australia to work or to join your family you can expect that the process will be much more complicated, time consuming and expensive.
An experienced and well qualified migration agent will never guarantee you a visa but they will help determine your eligibility and develop a strategy that is appropriate for your circumstances. In the end you will achieve your goal in minimum time and with least expense.
And if you do intend to work in Australia you will need to determine whether or not your occupation and experience is on the current list of skills that are in need.
The links below to the relevant sites for each category of visa.