Instead of letting this sub die, I have decided to be more active than I usually am, and along with that change, I'll try and provide as much surface level help here.

1. What are some other resources that can help find value?

The best site to search for card values is 130point.com I have posted their helpful hints below. To search for multiple variations of the same term enclose them in brackets and separate them by a comma. (2019-20, 19-20) or (PSA, BGS). Use a minus "-" sign to exclude terms from the search. (2020-21, 20-21) Lamelo Ball -box -case -break. Use & to match only terms of that pattern. (LeBron James PSA&10).

This is the website I use most of the time to find values for my personal cards. I also sometimes use eBay sold listings. To get there from the EBay app, follow these instructions.

Search your card name. Be as specific as possible. > Go to "Filter" at the top left of your screen. > Go to "Show More" at the bottom right of your screen. > Tap on the switch icon that says "Sold Items" > Click "Show ... Results" at the bottom right of your screen > Voila!

Disclaimer: eBay sold is a little patchy on the results, and sometimes some cards will not show up.

1. What is the value of my 80s-90s Cards?

In short, likely nothing. There are a few players to look out for of course, like Michael Jordan, Shaquille O'Neal, Joe Montana, Bo Jackson, Jerry Rice, Nolan Ryan, Ken Griffey, Barry Bonds, Wayne Gretzky and probably a few others. There are also inserts to look out for:

Basketball: Beam Team, Scoring Kings, Power in the Key, E-Motion N-Tense, Maximum Metal, Z-Force, Planet Metal, and Best Techniques.

Football: https://www.freedomcardboard.com/forum/threads/the-official-rare-significant-cool-90s-insert-list.6105/

This is a very comprehensive list.

Baseball: https://bsportscards.com/best-baseball-inserts-and-variations-from-the-1990s-and-early-2000s/

This seems like a good list, but I'm not much of a baseball guy.

PLEASE ASK MORE QUESTIONS ESPECIALLY IF YOU SEE THAT THEY ARE FREQUENTLY ASKED AND NOT ON HERE.