I will assume you don't know a lot about the current state of the hobby. If you do, I apologize.
If they are common cards, likely in full sets, or in a giant lot. You won't make as much as selling individually, but it takes a lot of time to list and fulfill orders. It may not be worth it for cards that will sell for $1-$5. You may also consider bringing them to a local card shop or a cosigner and seeing what they will offer you. You will likely be offered almost nothing because the shop has to put in the risk and leg-work to sell them. With that said, you don't have to take their offer and if you make note of which cards they offer to buy that probably gives you a leg up on what is worth selling yourself since they will only want the valuable or marketable cards.
If you sell a card for $1-$5 plus shipping, you don't net very much. eBay deducts fees on the total cost of the transaction (including tax and shipping). So it's best to assume you will net about 80 percent of the sale price.
Keep in mind that the standard for shipping hockey cards in Canada is lettermail. This is because of the price. You can ship a card in a toploader in a size 000 bubble mailer for 1.94. The minimum to ship it tracked ranges from $6-$10 using eBay's Expedited Lite service. So you can see how big the difference is.
If you choose to ship lettermail, you won't qualify for eBay seller protection. If a buyer claims an item hasn't arrived, they don't need any proof, you will have to refund them. With that said, most people have very few problems. The added sales usually justifies losing an item every now and then. For more expensive cards, you can list them with tracked services. A few extra dollars on a 50-100 dollar card won't make a big difference, but it will on a $1-$5 card.
Some 90s inserts can command high prices, but are very niche. More so, stuff from the mid-to-late 90s. If you have any flashy looking inserts of big name players, especially numbered stuff, I would pull those cards and research them individually. While a card numbered to /1000 might not seem limited in modern cards, with some 90s inserts they can go for quite a bit. Things like Topps refractors cards can go for a lot.
One avenue might also be to use comc.com - you send all your cards in, they scan them and list them for you. You can adjust the prices and all that, they catalogue all your cards and handle the fulfillment to customers. You can also list and auction your cards on eBay directly through COMC. Keep in mind that COMC's shipping prices to Canada through eBay are quite high, so while you might get more US customers, you do that at the expense of ruling out the Canadian market.
I would work backwards from 05, because that is where you're likely to find more valuable cards. Especially some of the 'Young Guns' rookie cards from 2000-2005, they can be quite valuable as there are some big names that weren't printed as high as they are now.
