I buy the odd mag now and then for an evening read or whathaveyou but generally, as Raymond says, its better to spend the time practicising rather than learning theory. At least that's what I find, and it's certainly more enjoyable that way.
There's also LOADS of stuff on the internet, and while you always have to do careful for information given out by randoms photography-related stuff tends to be pretty handy. I've been looking for tips on IR photography lately with a variety of different filters and Google turned up some very handy info, so it definitely can be useful.