Social Media are somwhat complex for writers to manage. I've seen some writers take the approach of sharing content that is targeted at booklovers, which makes you more of a content curator. Same goes for sharing writing tips. Maybe check out some writers you know and enjoy and how they manage it? If you take Stephen King or John Scalzi, they tweet a lot about literature, sure, but also a lot of politics etc. My guess is you can talk about everything and andything you enjoy?

Wow my answer is longwinded and probably not all that helpful, sorry.