Your putts tend to hop and skip instead of rolling smoothly toward your target.
Make sure the bottom of your putting-stroke arc occurs at the equator of the ball.
HOW TO DO THAT
Stack a dime on top of a quarter directly behind the ball on your target line (below). Hover you putter over the coins at address, and make your stroke. If your forward stroke is solid, you'll miss the coins. Don't cheat by exaggerating a descending blow.