Many websites offer how-to advice on just about everything. After registering as a guru on a specific topic, you answer questions from the public.
What you bring to the table: Documented professional expertise (or you can take a test to prove your knowledge).
Expect to earn: You won’t work full-time answering questions, but you can get more inquiries over time. At sites such as justanswer.com, more experience and positive feedback earn you more money per question, within a range of $2.50 to $25. Other sites, including ether.com, take a commission on the rate you set.