People often ask whether their accent will affect their IELTS score. The simple answer is no. Your score for pronunciation depends on how clearly you speak and how intelligible (easy to understand) you are.
So if accent is not important, what are the factors that affect pronunciation? I really like the explanation on this page from the Warwick University website. They look at 5 key elements of pronunciation:
There are some great tips about improving your pronunciation near the bottom of the page, but my favourites are: work on your mistakes, copy good models of speech, record yourself, slow down, and try to sound interesting / interested!