Reading greens may or may not be your problem. It can be argued that putting is the single greatest way you can improve your golf scoring, but there are a great many variables in putting that make it somewhat difficult to pinpoint problems unless you approach it systematically. First and foremost, are your grip, stance, and alignment. These must support a natural-straight down the line- stroke. Feet, knees, hips, shoulders should all be parallel with each other, and aligned straight down the target line. The ball should be positioned almost directly under, or very slightly outside your eyes, and your hands should be directly below your shoulders.
Another common flaw is the ability to accurately see and set the putter on your line. A good test for this is when you set up to the ball on a straight putt, set your club to what you think is directly down your target line, then, keeping the putter in this position, step to the rear and look down the line at the way your putter is facing to see if it's actually facing in the direction you think it is. Don't be surprised if it's not. Once these potential problems are straightened out, you can move on to reading the greens.
One thing to remember about green reading is that the majority of the break in your putt will occur in the last 1/3 of the putt. As the ball slows down, there is more time for the break to have its effect on the ball, so the slope of the green closer to the hole will have a greater effect than the slope of the green at the beginning of the putt. Here are a few of the things that go into reading greens.
- Uphill/downhill - Uphill putts will break less than downhill putts.
- Grain - Grass grows slowly in the morning and faster in the afternoon, and grows faster in the direction of the afternoon sun. This predominant direction of growth is the grain of the green and will deflect putts in the direction of the grain. You need to determine the grain of the grass on the green, and then know that the putt will be slightly deflected in that direction, especially on downhill putts.
- Angle of the hole - Obviously the ball will roll in the direction of the side slope of the green, but remember the hole is also sloped. The ball will be much more likely to go in from the uphill side than the downhill side. On the downhill side, the ball will be breaking away from the hole, while on the uphill side it will be turning towards the hole. Always err to the uphill side.
- Speed - There are many paths the ball can take to the hole. A ball hit harder will go straighter than a ball hit more softly. Short putts can be hit slightly more firmly to take some break out of the putt, so aim within the limits of the hole on short putts so that if there isn't any break, the ball will still go in.
- Surrounding terrain - Before deciding on the line for your putt, step back and look at the surrounding terrain. Is there a creek or lake nearby? There will most likely be an overall slope in that direction. Is there a hill or mountain? Putts will normally break away from those features, even if they are some distance away. Is there a greenside bunker? Often the sand from bunker shots will build up a knoll next to the bunker on the green and putts will break away from this. Get an idea of the surroundings before you examine your line.
There's obviously a lot that goes into putting and these are just a few considerations. My most important advice would be to make sure you can hit a straight putt straight. That way, a missed putt is most likely a speed or line problem and not a stroke problem. This will get you going in the right direction.