I have so many cards I had to take a dual approach....

I have all my higher value and foreign cards in 3-ring binders using the plastic business card storage pages that hold 10 cards per page. I just make sure to use pages that are listed as "archival quality" plastic so there's nothing to damage the cards over time.

My more common cards are stored in boxes, with each card stored in a protective plastic sleeve that seals the card and protects all sides and edges. Again, the sleeves are archival quality plastic so they don't harm the cards. This helps keep the lamination from peeling and protects the cards from getting scratched rubbing against each other, etc. I originally used boxes designed to store business cards that I got from U-line but they didn't hold the cards when I started putting them in the protective sleeves. So I switched to a slightly larger box that is really designed to hold baseball cards and these have worked out really well.

Some people go a little further, putting their higher value cards in protective sleeves and then putting them in 3-ring binders using the plastic storage pages designed for baseball cards with 9 cards per page.