Here is a two-step method:PoolBum said:I'm curious...what do you think is the best/most effective way to practice to improve one's 9-ball game?
First, try "progressive rotation." Start with a number of balls on the table that you think you can run out in order with cue ball in hand. If you fail, try the next rack with one fewer balls. If you do run out, try one more ball the next time. (You can get a random layout by breaking and then removing either the lowest balls or the balls you choose.) Try twenty racks, keeping track of your current number on the score wheel or wire. If you need more than nine balls, move on to 15 and plan a road trip. If you want to track your progress over time, write your final number in a log.
While you are doing the above, note which shots you are having trouble with. This is harder than it sounds, since if you miss a 75-degree, table length cut, it was the preceding position shot that you really missed and not the cut shot. After twenty racks, you should have twenty or so shots noted. Work on the repeated ones first. Make the shot into a "progressive practice" in which you change the difficulty of the shot according to whether you make or miss the shot. For example, you could make the shot a thinner cut or longer distance to make it harder. Practice the shot for 15 or so tries, or until you feel you have the shot mastered. (If you can't do the shot well enough to have gotten through a typical rack situation, consider other ways to play the position.)
Some other general explanation of the "progressive practice" method is available in the free "Basics Clinic" handout on the website below. One of the good features of this method is that it keeps you near the limit of your ability during practice.
Good luck.