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Another site in which you can put your sounds and get paid through PayPal: SoundBoard.
I didn't see it mentioned on the post. Thought it could be of some use.
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Field recording is the most crowded area of SFX libraries. For a passive income you may need to find more specific areas.
For contract works, without a portfolio, the only way is to go for your close circle and try to join projects of someone you know in person.
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