What should I look for when purchasing a quality album?

@OP - Invest in an ultrasonic record cleaning machine. Use streaming to identify recordings you like and then go tracking down the vinyl. I have heard vinyl recordings that don't sound good on CD but not vice versa. There are differences between different pressings of the same album depending on how old the stampers were and, also, sometimes different plants got different generations of the master. However, chasing specific matrix numbers is probably further along the spectrum of anality than your are at at the moment if starting to build a library.

@OP - Sorry for the delayed response, my computer was down when you posted previously. Regarding new records, yes, there is mould release agent in new pressings. And I don't know if it is inferior quality vinyl or manufacturing defects in the stampers, but a lot of modern pressings seem to be of poor quality. In addition, and I've said this before on agon - the vast majorty of modern vinyl records are derived from digital i.e. they are DDA  or at best DAA. Dependning on the quality of one's digital system, buying those recordings on vinyl is of dubious benefit.

@redlenses03. I did know a person who was obsessive about matrix numbers and, yes, there were audible differences between different pressings/masterings of albums. That said, a lot of it was a bit akin to "tube rolling" in that sometimes the sound was just "different" rather than being unequivocally better. Personally, I wouldn't sweat - especially when building a collection. And I would prefer to have a quiet and flat less good version of an album than a better noisy warped one.