I only try to keep up on my favourite ones or the ones I'm currently watching. The ones I'm currently into at the moment are Nakamura Shingiku's series (Junjou romantica, Sekaiichi Hatsukoi), Kuroko no Basket, K Project and Kill me baby.
Manga series... pretty much the same. Re-reading and keeping up with Nakamura's a long with Black Butler, Love Stage and Super Lovers!.
I wanted to keep on/ or up-to-date with future releases of other anime series too, like Hetalia, Seitokai no ichizon etc.