It just goes to show that I never know.
I thought of the mouse with the grape. I had a frame and needed a 5 x 7 with some green and brown in it to go there, and worked that up, and sketched it two or three times until I liked the position, and drew it. But my smallest watercolor block was 9 x 12, and it seemed a shame to waste a full sheet on a 5 x 7, so I drew out another frame on the other half and, with no planning, went into Painter and drew an eye and a scream and a neck and then, unable to figure out what he was screaming at, put a sock puppet on his tail. There was no planning, no forethought, no nothin'. Sketch took maybe a minute. Didn't even bother with the projector or the grid, just sight sketched it into the frame. The total time working on the piece was probably under thirty minutes, spread across a few hours.
At the time, I thought it was vaguely cute, and James said "Aw, he's the saddest critter ever. He's scared of his tail!" which from James is dancing-on-the-table praise. But I thought that like many of my pieces, it would be a small, cute, forgettable thing that would hopefully sell at Anthrocon for somewhere in the mid-thirties, framed. I didn't expect to sell a print of it within four minutes of posting to DeviantArt (a new speed record) and I really didn't expect to have 100+ comments to wade through this morning in the message section.
My point here is not to brag about the unexpected success of a particular piece, but to point out that you never know. At least, I never know. Sometimes the things I think are brilliant languish, and the ones that are quick throw-away pieces sell, sell, sell. But you can't even rely on that, because if you could, you'd at least know by inverse--"Aha! I'm ignoring this, so it will be Wildly Popular!"--and you don't. Sometimes the ones you think are pretty cool really do appeal to people, and sometimes the ones you toss off in twenty minutes vanish in ten.
It's been not quite a decade since I made my first commercial sale--which has, thank god, vanished forever from the internet, wretched as it was--and I still don't ever know quite what sells. Some of the most popular pieces, I saw coming--I knew the Wockwurm was something special--but some of 'em blindside me completely--I expected 'em to find the Cuttlefish Hat propped up in a forgotten corner of my studio after I died. And I really liked the "Snogwoggler" but I couldn't sell that thing for love or money, and finally gave it to James's sister for a Christmas present.
There's no element that I've found that will automatically sell a piece. Not even sock puppets. Possibly those little cardinals--we're two for two--but I'd need to do a few more before I could judge. (Come to think of it, I need to do a few more anyway.) There's no magic bullet. Even frogs. Whimsy might be a magic bullet, but whimsy is not something one can simply sit down and include like a sock puppet. You just sit back and realize it's whimsical, or you sit back and go "Jesus, I must be on crack today." Whimsy is like a butterfly juggling teacups, chainsaws, and very small mammoths. Even assuming you could get 'em that small, once you close the shackles over it, it's no longer juggling and all you've got is a mad butterfly with a chainsaw. (Note early comment about crack.)
There's a truism in furry art that sex sells. Let me disabuse you of that notion. It's more likely TO sell--you only have to hit one person's fetish, after all--but they're rarely one of the Wildly Popular. (Although, again, you can't rely on that, either--we couldn't keep one or two of the Caliban prints in stock last time, and we were running off fresh ones every few hours. Oddly enough, they were both bunnies. Go figure.)
I remember talking to another furry artist at a con once--one of the good ones, but alas, I cannot remember who, specifically, beyond that--who said that she'd run off a half-dozen prints of a four-armed skunk goddess carrying cleaning supplies, not expecting anything at all, and sold out of 'em practically before the doors had opened. "Who knew?" she said, shrugging.
And that's the thing. None of us know. This is why I bring the printer and disks full of art if I can. Most of the truisms don't work for me. "Foxes sell." (Never had a popular fox piece.) "Wolves sell." (Ditto.) "Tigers sell." (Mediocre sales at best.) "Sex sells." (See above.) "Native American stuff sells." (Okay, the Slug Totem did pretty well, but I dunno if that actually counts.) The only hard and fast rule that I have ever managed to establish is that if I give it to James's sister for Christmas, people will start asking to buy it afterwards, a rule that, while so far unbroken, doesn't do a helluva lot of good for my purposes.
But hey, that's what keeps it interesting. If, like Thomas Kinkade, I could throw off a piece on a particular theme and rest, confident that it would be a blockbuster, I might be richer, but my work'd probably be a lot more boring, and I doubt I'd enjoy it so much.