You have 56 sales out of 452 listings (sales+active listings). That's reasonably good. I think a mistake people make with eBay is not realizing how long it takes for the average BIN item to sell. With a lot of categories, eBay is a volume game. The only way to increase your monthly profit is to increase your volume. If you list things at market value, it's like a rotation. Everything sells eventually, but to increase your sales you need to increase your inventory.
Your pictures are good. My only criticism would be to make them a 1:1 aspect ration (a square) since that is what is used in the default search. Maybe consider getting a piece of seamless white photo paper, or even a piece of white poster board to create a seamless backdrop. I think your photos are good enough that there would only be marginal gains, but it would be something to consider.
As others have pointed out, titles are important. The first few words are the most important. For big ticket items that haven't sold, that you think are priced competitively, try searching for them yourself on eBay. Click sold listings. See if there are any terms that are missing from your title compared to ones that regularly sell. Also observe the titles of the listings that appear closest to the top. See if there is anything you're missing from your title, or anything you can improve.
You should either enable the best offer function, or aggressively use the send offer to buyer function. It's a lot easier for a buyer to commit to buying something if they feel like they got a deal. There also might be cases where if something is listed for a long time, other sellers might undercut your price. So the best offer function helps equalize against that. Again, there should be some wiggle room in your pricing structure. I don't know if you're reselling items to make money, or just moving out collectibles. If it is reselling, you should take a position where if an item sits around, you can take an offer on it lower than your ask and still turn a profit. It basically shouldn't be a situation where you have to get your BIN or you've taken a bath on the item.
The only exception to this would be low priced items. Something around 10-15 dollars with free shipping is going to have a thin margin. For a $10 item between lettermail shipping, supplies, and eBay fees you're maybe looking at $5.50 in costs. So that leaves $4.50 for profit and the cost of the item. Someone who would have bought at $10 might try to be strategic and send a $7 offer, and be turned off by you countering or declining, because $3 on paper seems like such a reasonable amount. But with a low priced item, it makes up almost the entire profit margin. While this is an extreme example, it shows why the best offer isn't viable on lower priced listings.
At least in Canada, I think free shipping is fine. Anything you list, you should have some wiggle room on. In my experience, you're looking at most a $10 difference in worst/best case scenario with shipping. With calculated shipping, you also risk overpricing the final product for people on the higher end of the shipping table. Smaller items that go lettermail cost the same anywhere in Canada.
You have about 400 items for sale. If you really aren't satisfied with the speed of your sales, you could spend an hour or two checking the price of your items against both current listings and sold listings. Price is tricky, because there are some niche items where there are so few buyers and sellers, that lowering the price won't trigger a sale. But for more common items price can be a big driver of business.
