Thanks, guys (and girl). I really should make it my priority to not re-injure myself, I guess...
Garrett, thanks for the recommendation. According to the library database a library here in Iceland actually has "Low back disorders : evidence-based prevention and rehabilitation" by Stuart McGill. I'll have to order it, though, and it'll probably take a few days, but looking around the guy looks pretty solid.
Planks are a good idea as well, I'll definitely be implementing them.
About the isometric holds... do you mean like in a cable machine, standing, holding the cable to my side and not letting it twist me?