Use the line on the ball to help you aim

Most modern golf balls have a line (sometimes an arrow) on them to help with alignment when putting. Even Tiger Woods uses this method to help with lining up puts. You can buy a tool in most pro shops, on line shops or even eBay that you can use to put a line right on the center of the ball if the ball you use does not have one.

With this method if you putter has a line on it (or you can draw a line on your putter) this is usually where the sweet spot is on the club you can line up the 2 lines ie the one on the putter and the one on the ball. This way when you get down and read the green you can pick your line and use the arrow on the ball to aim along this line. When the ball is put on the green you can then step back and check that the line on the ball is pointing aling the line of the put, if not you can re-adjust the aim. Now when you stand over the put all you have to do is line up the ball and the putter lines so you know that you are aiming on the line you want.