When deciding whether to give a band 7 in IELTS speaking or writing, one of the things that examiners look at is your use of collocations.
'Collocation' basically means using the right words together. Many students know a lot of nouns, but they don't always know the right verbs to use with those nouns.
Here are some useful 'verb + noun' collocations:
- to make a mistake (not 'do' a mistake)
- to do/carry out/conduct research (not 'make' research, not 'a' research)
- to make/take/reach a decision
- to have/gain/lack experience
- to have/face/experience difficulties
Think about this, especially when you are writing essays. Check in a dictionary to make sure you have used the right verb with the right noun.