Sponsors on Instagram seem like a solid way of doing it if people are active, engaged (and obviously those people are transferable to Insta) - if they're just spam accounts, and not real people, then that would be a lot more difficult.
When you say 'utilise' what do you mean? Monetise?
BAsed on what you do, I think some Amazon Aff work would be good. Talk about books you've read and link to amazon. If you have 200,000 followers and can get engagement from 1% then thats 2000 people going through to amazon. Its probable that 5% of those people would buy something from amazon in the next couple of days anyway. Thats 100 getting you AmAff earnings.
@Jon says it right. Its all about the engagement. You also want to make sure you don't flood your audience with tons of links. But I've just seen you auto follow anyone who follows you. Based on that I'm not sure your audience will be as engaged as others. You follow over 100k users - how do you engage with them?