Write without pay until somebody offers pay. If nobody offers within three years, the candidate may look upon this circumstance with the most implicit confidence as the sign that sawing wood is what one was intended for.
I was lucky to start writing for pay from the beginning. However, I was not so lucky that for the first few years that pay was about half-a-penny per word. Twain’s advice hits especially close to home considering my day job is in the wood sawing field.