When putting, if you struggle to hole putts due to missing the hole to the left or right a great drill is to practice putting towards a tee instead of putting into a hole.
This makes you focus more on accuracy. Practice putting with just the left hand then the right hand and finally with both hands, holding the putter as normal.
Putting one handed helps you to build control with each hand separately as sometimes one hand will want to keep the putter face square and the other hand will want to turn which will open or close the clubface.
Once you are confident that both hands are keeping the putter face square now you should hit your putts more accurately with your normal hold of the putter.