There are a few ways. You can do those affiliate programs but you probably won't earn much. You can also do a service type thing if you're good with creating things. For instance, if you can produce music then you can sell your music or offer your services to others. If you're good you might be able to earn a bit. You can also do graphic design work, like designing album artwork, doing logos and signatures etc. If you get decent at it you can earn a bit. I have a friend that does logos and artworks and does merch and she earns a lot. It's something that does take a bit of time but will probably earn you the most online