The most effective way to learn this language is to live in an English-speaking country, and Australia is definitely your best option because you will find different types of courses that adapt to your professional needs.
English courses in Australia for international students are called ELICOS (English Language Intensive Courses for Overseas Students) and there may be several types of courses depending on your objectives such as General English (General English), English for Academic Purposes (English for Academic Purposes), English for Specific Purposes (English for Specific Purposes), English Courses for Certification, IELTS (International English Language Testing System).
It is the best known certification worldwide to test your knowledge of the English language, usually requested in higher level studies, PET (Preliminary English Test), FCE (First Certificate in English, CAE (Certificate in Advance English), CPE (Certificate of Profiency in English).