9 Ball break:
I've never really mentioned it before because I didn't think it was something unique. I'd guess anyone who's toyed with the break has done it. You can tune your break and find good breaks by finding aim points in the rack. You can aim at balls, the spaces between balls(half ball hit), or fractions of most balls in the rack while hitting the 1B. You can use different spins to do different things like parking the CB or going to 1 or 2 rails for shape or to re-smash the rack. The rear ball, the next to the rear two balls, or the space in between the 9 and a neighboring ball can all produce. It depends on your goals for the CB and what you wish to accomplish. The 1B is more wired into the side with 9 on the spot, but it can be done most of the time with 9 on the spot too.
If you're doing a cut break, from anywhere from the rail to about 1/2 diamond out you can pretty much shoot for the third diamond on the end rail with some low right. This will park the CB about a foot from the 1B, make the wing, and a big chance to make the 1B in the side. Your goal is 1B in the side, which lets you really tune how you are breaking. Once you get so you can make the 1B in the side 4/5 times you know you are breaking consistently. While practicing do this with a template for consistency. Even if you switch to a wood rack, this break still works well... but it's harder to make the 1B in the side, especially if there is any space in the second row (row behind the 1B).
I mention this
gap between the second row balls because if you're playing in league this second row space is almost always there and it can be hard to freeze those balls if the cloth is old and has a "memory." I feel that this gap is more common on tables where 8B is played a lot. I think the second row balls try to "squeeze out" more on 8B both due to more rack mass and second ball breaks being used. The result is the cloth is crushed outwards, making the second row cloth divots more oblong, pointing at the side rails. The balls want to roll out and not stay frozen as they would with a single divot.
This sounds silly but if you've ever replaced cloth on a table, there will be fine lines on the slate where you can see the track lines of a break and where the balls go. If you play more 9B, you can still see faint lines where the 8 ball break tracks. I suggest taking a reference picture if you want to study.
In 9B if any gap exists between the second row, like if you could fit a cigarette rolling paper in there, you're much better off breaking closer to where the pro break box is, or at least 1 diamond off the rail. Find the exact diamond line and put either of the CB's edge on that line. If on an unfamiliar table, break hard because a wing ball isn't guaranteed if that gap is in the second row.