Oh I didn't even see the section, my bad. Do by tactical problems you mean "which move is the most logical/best" or "mate in three moves" sort of problems? If so I already do those. =]
Ya, mate in three/win the piece enprise/etc are the ones I was talking about.
Weapons of Chess is a nice overview of the common pawn structures but for a deeper study, I'd recommend Pawn Power by Kmoch.
"My System" by Nimzowitsch is ok, but I'll bet there are better ones out there. Nimzowitsch tends to be a little too general in his advice rather than formulating strict rules to go by. You also have to remember that his whole philosophy was centered around prophylaxis and surrendering the center - not something you would want when building strong pawn structures.
If you want a good book on pawn structure and positional play in general: Winning chess strategies is good as well as My system.
My absolute favorite book right now is Pawn structure chess maybe a little advanced but for future reference it is a fantastic eye opener.
I can tell you right now though that dropping pawn structure books and working on Tactical problems would improve your game exponentially.
Edit: Your question is fine (and much better content than half of the threads here) but should probably be under "chess books and equipment" forum not general discussion.