’I want to sound more natural in English’ is something I often hear from people who come into school for an interview. Different people have different pronunciation issues – some have problems with the individual sounds of English, others sometimes put the word stress in the wrong place, or stress the wrong part of a phrase. Having a teacher who can correct you and model the correct pronunciation for you is the best thing that can help. That said, there are also some online resources for working on pron. outside class.
The Cambridge English site has various activities on pron.
You can search by level. Here’s B1/ B2: https://www.cambridgeenglish.org/learning-english/activities-for-learners/?skill=pronunciation&level=independent&rows=12
Here’s a nice little activity on intonation
https://www.cambridgeenglish.org/learning-english/activities-for-learners/c1p065-intonation
These exercises look at individual sounds.
2 :https://www.cambridgeenglish.org/learning-english/activities-for-learners/b2p067-bold-or-bald
3: https://www.cambridgeenglish.org/learning-english/activities-for-learners/b2p085-stars-or-stores
4: https://www.cambridgeenglish.org/learning-english/activities-for-learners/b2s004-syllable-stress
This is aimed at C1 but works for other levels:
https://www.cambridgeenglish.org/learning-english/activities-for-learners/c1p065-intonation
The BBC has a huge resource. It’s quite long at 75 minutes but gives you pretty much everything you need to know about sounds.
https://www.youtube.com/watch?v=QxQUapA-2w4