If you want to apply for a student visa then essentially you need to approach an educational institution and obtain an offer of enrolment. Then you need to ensure that you have enough funds to live whilst you are studying in Australia. After that, you then need to apply for the student visa. If you have sufficient funds and an offer of enrolment, then you should be granted the visa.
If you are enrolled in course for example three years, you must remember that your student visa does not last three years, it probably only lasts for 1 year. This means that must apply for another student visa before your current student visa expires. If your current student visa has expired, then you must apply for another student visa within 28 days of your first student visa expiring. If you don’t apply for another student visa within the 28 days, then you won’t be able to apply for another student visa. Further, you will have to leave the country, and you won’t be able to come back to Australia for another three years because the department of immigration will exclude you from Australia for three years.
So please remember to check as to when your current student visa expires.