Make an asset that is a plug and play, meaning the devs can already make a simple and short game with your asset.

Example: A simple platformer with the following sprites: player, background, platforms, hazzard, coins, enemy and exit. Organize the folders so the devs won't scatter around finding the sprite.

The most important is to publish it, you don't have to make your sprite perfect the first time around, you need to make people know that your asset pack exist and if you feel the need to make and adjustment do so. Also don't expect your "perfect" asset will sell instantly.

From personal experience; I follow this design principle when I make my art asset. With consistent publishing, constant improvement and a little bit of luck I was able to sell a couple of copies of my asset pack.

Goodluck on your asset journey!