On is the correct preposition for this question.
5 Things to Avoid While
Improving Your English
Don't be Afraid to make mistakes
Cause we all make mistakes
Don't be Ashamed to speak up
Just start speaking in English
Don't get frustrated with yourself
Instead relax & enjoy yourself
Don't Compare yourself with others
We all are different & unique
Don't Learn everything at once
Focus on one thing at a time.