Originally Posted by iacas
Putting is three skills.
1. Start the ball online.
2. Hit it the proper distance.
3. Read the green properly.
Figure out which of the three you're weakest in and work on that.
Just to give you (the O.P.) a few ideas of how to work on these, I'll share how I improved in these different aspects myself.
1. For this I got a chalk line from Home Depot. It was about $5 and the chalk was just as cheap. I took this out to the practice green and found a slightly breaking putt about 10' in length. I would then hold the end of the chalk line in place with a tee from where I would start the putt, and stretch the line across the intended line I wanted to start the putt on. You then "snap" the chalk line (stretch it up and release) to put a faint line on the green. Repeat until the line is appropriately visible. I would then stroke putts on this line to make sure I was starting the putt correctly, adjusting the line until I started making the putts. The line is easily wiped away afterwords by sweeping your towel across the green.
2. The best practice for this was to play a game called 7-up with my teammates. We would pick a long putt on the practice green, usually 50' or more, and all putt to that hole. The person closest to the hole got 1 point, and everyone had to 2 putt or they would lose a point. This game can also be played trying to get up and down, but a small (candy bar in the pro shop usually) friendly wager always made you concentrate on the putts.
3. This is something that was hardest for me, but the best way for me to learn better was to guess in my mind how a ball would react rolling along a green before putting. I would picture someone else putting from the same spot as me and would watch their ball go up and down the hills and valleys of the green. Careful observation and practice are what gave me a better sense of how greens break, along with a few general "rules". Greens usually break more when they are a faster speed for the same slope, they usually have two or three drainage areas (where water runs off the green) that will be low points, and most importantly that I personally always prefer uphill putts to downhill ones. Just a few things to mull over next time you practice.
Those three things helped me the most, and they might help you too. The only way to know for sure though is to try it out for yourself. I did find Dave Stockton's books on putting to be helpful myself (especially the idea of looking at a spot to roll your ball over) and his ideas about a number of different things seemed to be easily understandable for me. They would be a good place to start if your local library or used bookstore has any of them.