Resharing my artwork online (in blog/forum/imageboard/social network) is allowed under these conditions:
1. It's done for free. If you charge your users to view artworks in your site then I'm not allowing you to host my artwork. Charging for premium account is fine as long as you still provide access to the artworks for non-paying users.
2. Linking back to the artwork's corresponding Pixiv page. Don't just provide the artwork ID and artist name.
3. Resharing is allowed by default unless stated otherwise.
I know my works aren't that beautiful but it doesn't mean you can monetize on them without my permission. If you do I'll kill you so hard that you'll die to death. Nah! Just messing with ya. I'm much too handsome to be a murderer. What I'm saying is please be nice and fair to me and my works.