Some things I figured out somewhere between C-player and B-player:
1. When using running english, don't fall into the trap of always adding topspin to help the ball run. Some situations call for topspin but in a lot of cases hitting with pure sidespin (no top) will actually get better results than adding the top. It's like the help you get from the topspin... doesn't make up for the loss of sidespin you get by 'diluting' your left or right english with a higher tip position.
2. There's a sweet spot for sidespin (like like for draw), it's about halfway between the center and edge of the ball. On a centennial ball, try centering the number on the ball and then trying to make your tip hit the black outline circled around it. That's pretty much your ideal position. You can go a bit further out but it's close to a miscue and overkill.
3. Cheating the pocket (so you can hit the OB a bit fatter or thinner) makes a HUGE difference on many shots. For example, say you have a shot nearly straight into the side, but the wrong angle. You have an angle that will send the CB slightly to the right, but you want to hit high left and make the CB hit the rail next to the pocket and spin as far to the left as possible. The secret here is to cheat the crap out of the shot, hitting the OB as full as you can without missing the shot. Then the CB travels in a straighter path to hit as near the side pocket as possible, and the left will have maximum effect.
The exact same stroke here (with different amounts of pocket cheating) can literally make the difference between sending the CB 4 feet to the left or 1 foot to the right.
4. Softer is better, spin takes better when the ball hits the rail moving slowly. Not always an option but worth remembering. There will be situations where you can trade off better spin effect or longer CB travel. You have to figure out which is more important for getting a nice angle on the next shot. A longer but straighter shot might be easier, therefore it's worth hitting a little soft just to get the spin to take nicely and carry you straighter towards the next shot.
5. When shooting soft, especially when the OB is near the rail, you might find you get better results with low running english than middle or high running english. If you use those other options, the CB slides across the cloth and starts rolling, essentially picking up topspin. By the time it arrives at the object ball, it is a mix of sidespin and topspin. You'll remember from point 1. that this is not always ideal. So what you do is hit a little low with running english. This prevents the ball from picking up that natural roll, and by the time it arrives at the object ball it spins as if you'd just hit with pure middle-left or middle-right.
