polish up
US /ˈpɑː.lɪʃ ʌp/
UK /ˈpɑː.lɪʃ ʌp/

1.
oppoetsen, verbeteren
to improve something by making small changes to it
:
•
You need to polish up your presentation skills before the conference.
Je moet je presentatievaardigheden oppoetsen voor de conferentie.
•
She spent hours polishing up her essay.
Ze besteedde uren aan het oppoetsen van haar essay.