Are you happy with your writing sales?
If you're not, chances are that you haven’t got a big enough inventory.
Let's see how this works for other business people. (If you're a creative, and you're trying to sell your work, you're a business person whether you face the fact or not. :-) )
I'm always shocked by writers who fail to write for inventory. Photographers shoot stock images, and artists build sketchbooks of inspiration, after all.
The above post is as relevant today as it was when I wrote it seven years ago, perhaps more so.
Build your writing inventory. You're creating your own goldmine, as you'll discover in the months and years to come.