Instead of figjamming, I am going to give you some tips on how to progress.
First, you have to have some degree of natural talent. I've seen a few bowlers that will never be "good" because of lack of natural talent.
If you have that talent, find someone that can help you with your approach, swing, and release. Repeat these until your foot at the foul line is within 1/2", side to side, each time you slide (for the same starting position). Mark your starting spot with your slide foot so you can compare to your finishing position at the foul line.
PRACTICE. Bowl at least 25 - 30 games per week, including your league games. When the pro's are working on their game they bowl 40+ games a day. In your practice sessions, try different things. Start with an extreme outside line, then work your way to an extreme inside line 3 boards at a time, staying on each change until you're hitting the pocket. DO NOT WORRY ABOUT SCORE IN PRACTICE. Use your first ball to shoot 10 and 7 pins, then your second ball to hit the pocket. If your center will allow it, make a layer of two pieces of white adhesive tape, cut to 2" width - center the tape on your target board and practice hitting it. By the time you can hit that 2" piece of tape 9 times out of 10 you will be well on your way to being "good". -- JohnP