I check for even compression in both holes, and how that compression compares to numbers earlier in the season.
I check the domes for anything unusual. Same with the bore...check for scoring (though the compression check should cue you in)
I inspect the sleeves and casting for cracks.
Check the O-rings if you have them.
Check for signs of piston slap (on bore and piston)
Inspect the circlips and wrist bearings.
Look at the rings.