This is simply the way I used to get most of the Ace Score objectives:
Luna was my go-to Peggle Master for a large portion of the Ace Score objectives that I did not earn through regular playing. The reason is this: if you have her power activated for the final shot where you hit the final orange peg, you can potentially rack up hundreds of thousands of points in that one final shot if you prepare for it properly.
It does take some preparation to get to the point on a level where you have at least one green peg remaining, and you are down to at least 1 or 2 orange pegs. Her power will activate for 2 turns, so having a minimum of 2 orange pegs left will guarantee you will be able to take advantage of this method (as long as you don't miss!! haha).
Load up the level you want to play, and take a quick survey of the level. Take note of where the green pegs are and decide whether or not you can take out most of the orange pegs without using up both of the green pegs, if you can then go for it! Once you start play to clear the orange pegs as quickly as possible. Once you are down to the last couple orange pegs, you can shoot to activate that green peg you have been saving. Then with the multiplier on its highest output, you can really get some huge points hitting all the ghost pegs.
The key here is on your final shot aim for the final orange peg so that you bounce the ball off the peg to maximize the amount of ghost pegs you hit. The more you hit, the higher the final shot score will be. I often found that I could generate final shot points of up to 300k and sometimes even 500k (and that was before it added in the bucket bonus points).
Most of my final shot scores with Luna were generally more than enough on that shot alone to hit the Ace Score objective for any given level.
There are of course, plenty of other ways to generate high scores on levels, but this method (for me) was the one that I found to be the most consistent, and the way I was able to generate the highest scores on levels.
Good luck. (especially with those celestial realms objectives! yikes, those were really tough)