@jts @bill @boidhre Thank you for those advices.
I took mobile versions of Cho's Enciklopedias from
http://tsumego.tasuki.org/ and I use them on my smartphone when I have short gaps of free time.
I browse through goproblems.com regulary and Graded Go Problems for Beginners on my desktop, too.
Regarding playing with bots, I've got Champion Go installed (Crazy Stones is iOS name of the program) but I never used it much since I'm not aware which kind of habits I'm gonna develop if I play with bots (even strong ones as Crazy Stones algorithm is). I would like if anybody can write a few words on low sdk player playing with bots and habits developed from that.
@jts I never seriously considered blitz or 9x9 games. After your post, I definitely will. Thank you.