As spotty cats said, "condition" refers to healthy body condition, not too thin or too fat, well developed muscle tone.
Health probably would include some things like clean ears, clean, bright eyes, a healthy looking/ feeling coat. ( some of that is of course also related to grooming but for example the coat quality is also from diet)
In addition to the things she mentioned about grooming, you should clip the claws before showing. I usually do it a day before, so the edges get worn down a little.
It's acknowledged that there's no breed standard for HHPs and beauty is in the eye of the judge and admittedly subjective. So there's no standard of points about markings etc.
I think some of those HHP cats at that link are quite striking domestics. I like that red classic tabby. and the tortie. The cat who won Best, though the photo looks like just a sort of plain blue mackerel tabby, has beautiful gold eyes.
And no doubt those cats had a great personality too. Personality seems to count for a lot. They want to see a friendly cat but beyond that, it can be different kinds of personality . They do like cats who really go for the toys , but also cats who are not as energetic but love attention, rubbing their head on the judge etc.
I agree with SC that if you got the cat from a breeder, check with her/ him about showing your cat in HHPs.
Of course if it's a known purebred or purebred-looking cat adopted from a rescue , then it doesn't matter. Obviously CCA does allow cats who are / look purebred to be shown in HHPs
One thing you could do to prepare is watch some videos of judging, especially judging HHPs... and watch judging cats of your breed since the judges may instinctively handle the cat the same way they would handle that breed normally even if they are not judging the cat by the breed standard.
Then set up a table and pretend to be the judge. including play with the cat with teaser toys like the judges use... get a few different kinds - fur, feathers, sparkly stuff etc. Then if possible have friends come over and play the judge so the cat gets used to someone else doing it. After every little practice session give the cat a small treat.