If a 3 or early 4yo hasn't had a huge jump up (one of those ten point jobs), then I like it when they have like a half point forward move. 7-1/2 to 7. Then I'm looking for a pop.
I also think its big when a 3 or 4yo comes right out and breaks through its previous years top by just a little. The next one is probably going to be a new top.
2yo and 3yo pairs are good, depending on the overall context (the pair shouldn't be a big move forward).
If a horse with a grass pedigree runs so-so or bad in its debut, they can move up big time second out at a price. I also like grass pedigree horses off lousy dirt debuts switching to grass. HP