juicyjojo

Here is what I do:

1. borrow some English books from the library
2. get your voice recorder ready
3. read the books out loud and record
4. listen to the recordings and see what kinds of words or phrases in particular that you need to improve on

Since you have been practising English for such a long time, I am pretty sure that you could tell from what is a good accent or bad accent.
you can also do it without recording, just keep reading to yourself- practise makes perfect.