Getting a good score in the IELTS exam depends on the purpose of taking it. Suppose you are taking the test for immigration, then a good score depends on the country or visa category you have applied for. For instance, if you are applying for a PR in Australia you must score at least 6 bands in each module to be eligible to apply. Based on the score you get your points in your application. A score of 7 gives you only 10 points while a score of 8 on each module gets you 20 points.
If you have given the IELTS exam to study for a course overseas, then you should get a score that is acceptable to the country or university you are applying for. Most universities require a minimum score of 6 to 6.5 for eligibility to apply for a course.