Before you decide what to fix make sure you know what is wrong.
Be as objective as possible and write down what part(s) of your putting need some work.
For example: distance control; accuracy; rhythm; green reading; consistency; short putts; long putts; all of the above.
Once you have identified the problem then you know what to focus on when you apply the fundamentals.
You should then re-visit your list after you have a better understanding of, and applied what you have learned as you proceed.
It will certainly help you better understand and apply the tips if you follow the simple steps as described in The Fundamentals of Putting.