I too have quite a physical collection but sometimes I just remember about where I could have seen something and then I look it up online. Because as you said, Czarine, the wikis et cetera often contain little reference and your best chances are the comics. Art books, gatherums and so on... well, the some do feature several characters but sometimes you look for a specific outfit at a certain time or even a pose. And for poses I sometimes check other references. I don't own one of these little wooden dolls, so I have to look for photos how something looks in reality. Or one has to pose yourself, you know, if you can't find something quickly. Though you have to translate it a bit back to Elfquest body proportions - and I rather fit the classic Tolkien elf or even a high one, but not the EQ wolfrider type.
I spent a good part of time finding an idea (though it sometimes just hits me) and then the major part on undusting my "skills", putting the tech together, and then, well, drawing, colouring and never being satisfied with the result and ending up in correcting. And that is a benefit of vectors, it's never as easy to draw like using a pencil or a tablet plus pixel graphics, but you can correct the hell out of it.
The new art book (Kickstarter one) contains a couple of characters and art pieces but I'm not sure if it is sorted at all or if it has an index so you could look for a specific character.
It would probably be helpful to make a collection with a list of characters, their outfits and some of their mane facial expressions and some typical poses.
edit: the figures and busts. Not always a full body reference but... it's a possibility.