What should I look for when purchasing a quality album?

time out!

@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.

yoyoyaya I have been looking at those ultrasonic cleaners. It seems that even brand new record albums have plenty of dirt and debris on them.

I search BandCamp at least once a week (good for files and streaming, too). I use Discogs quite a bit, and keep some of the collection catalogued there. Discogs uses the Gold Mine rating system.  I have 2 used record stores near me, and stop at both every time I'm in town. I probably am buying 80% through BandCamp, Discogs, Music Direct, and etc. I used to buy through subscriptions, like R. Stevie Moore's catalogue, and some of the artists I am interested in only release on cassette, files or CDr. I follow the music, some of the media is not up to Audiophile snuff. It is somewhat common to end up with variations (pressing plants and other variables) of the same record. It's like collecting stamps or coins, you're going to have some "place holders".

I would encourage you to create an account in Discogs (free), and even use it to catalogue the albums you have. Most albums have multiple releases, and sorting through all the releases to find the one you have is an educational experience. I learned about the information in the run out groove and how to decipher it. That helped me figure out which pressings may be better than others of the same album. It also tracks the value of your collection (based on past Discogs sales), and you can set up a “wishlist “ of albums you’re looking for. Their marketplace is also very good and very vast.

Goldmine is an excellent grading system, but remember, its use is based on the honor system and interpretation/judgement/assessment of the person grading the record.

Best of luck and welcome to the wonderful world of vinyl!!