On a practice green, place five to ten golf balls around a hole, creating a three foot radius. Go around the circle until you can make every ball on the first stroke. When you get comfortable with making those, set a goal of making 15 in a row, then 20, then 25. If you miss one, start the count over until you make it to the number you set.
Practice good putting pace by placing those five to ten golf balls around the hole, again creating a three foot radius. For each putt, decide if you want the ball to just fall into the cup over the front edge or to hit the back edge of the cup before falling in. Again, set a number of putts to make in a row while doing this drill. This drill will teach a golfer how to control the speed of putts, which will help when faced with downhill and uphill putts. Downhill putts are the ones that just fall into the front edge of the cup and uphill putts hit the back edge before falling in.
To really focus on the line of short putts, place a tee into the putting green so about 1 to 1.5 inches is visible. Now place balls in a three foot radius around the tee and focus on putting each ball to the tee. This drill gives no room for error like a golf hole does--one inch off line and you will not hit the tee. Continue with picking a number of putts to make in a row.