You should use a Registered Migration Agent as it is their profession to know the visa application process. This will help you have a hassle-free application process and ensure you lodge the application correctly.
Visa refusals can be devastating for applicants; resulting in restricting applicants applying for another visa, and often results in the applicant having to depart Australia. The Department of Home Affairs does not refund visa application fees, and as a result a poorly applied application, or an inappropriate application can cause financial and personal stress that a properly constructed appropriate application can alleviate.