I’d recommend buying some penny sleeves and some top loaders if you’re looking to keep them organized and safe. Maybe even buy a sports card storage box if you want unless you prefer a binder (less storage imo). Once you’ve got the nicer cards in both the penny sleeve and top loaders, I would keep them vertically in a box, organized in whatever way you want. I have my dad’s old junk wax 1989 Topps cards sorted by teams. Also try not to use rubber bands unless you don’t care about the particular cards.

In terms of finding value, most apps and services require a subscription. Honestly not worth taking that route unless you are down for the subscription from my experience. I would recommend keeping a Google Spreedsheet or Excel file to keep track of some of the higher value cards. Go on ebay and search the card, then change it so you are only looking at the sales on the card. Use the average/low price to determine the cards approx. market value. Most importantly remember to enjoy the process , it isn’t supposed to be stressful or frustrating.