If you’re struggling with consistency on the putting green, the first thing to look at is the position of your elbows.
Get this right and you’ll find it a lot easier to swing the putter freely and smoothly back and forth, using your shoulders to power your stroke.
Where to position your elbows in your putting stroke
The ideal position for your elbows when you swing your putter is slightly bent and lightly against your side.

If your elbows are sticking out, it’s easy for your arms to swing independently from your shoulders. And that’s when you’ll mishit putts or generally swing the putter inconsistently.
And that means you’ll hole fewer putts.
From behind, it should look like the putter shaft is an extension of your forearm, pointing towards your elbow. By making sure your forearms are in line with the shaft, the head of the putter is more likely to follow them down the line during your stroke.
Give it a go and let me know how you get on!