Get the balls out and start sucking. Get a multiplier going for the shardstrom, try not to let anything fall past your paddle (since that reduces the multiplier) using the shield. Also the Shardstorm bonus applies to how many times you've used the shardstorm (I think), it's not huge, but it can add up, but do try to save it for key moments (using it at the end of the level will not use the whole gauge but still give you the bonus). There's also a 10 million bonus for clearing the stage without the balls bouncing off a wall, I think that can be done on the rotating thing but I haven't done it yet.
That's pretty much all the tricks I've learned, feel free to correct any misconceptions.