As an Independent artist, it is never an easy to decide this question — whether to or not to allow free downloads of your music. Well, personally, I feel there are different levels of career growth for all the indie artists, and they have to decide after weighing the pros and cons of offering free downloads of their music to their fans and listeners carefully.
It is a great promotional tool, and you can connect with your fans by offering a free download, which may prompt them to buy the full album that you have released.
It offers a gift of appreciation to the current fans, who have spent time and money to listen to your music. It gives them a sense of prestige.
It helps in spreading the word about the new music and album in the current fan base.
It can also be used to offer postcards or giveaways at live gigs so that they could come back to your website and download the song. This, in turn, gives your fans a connection and you a definite number of audiences that you have.
With every free download, you are losing potential revenue from your music. You could be at a financial stage where this might be a problem for you.
Because a downloaded file can be shared, the loss of revenue could be exponential to your overall earning.
Though the pros outweigh the cons, the decision to offer free downloads of a solo song rests with individual Indie artists, and there could not be a rule of thumb about this issue.