Your situation sounds quite typical.

Tactical exercises, drills, diagrams -- whatever you want to call them --
are a time-tested way to improve.

They can be very tedious, but they are also very effective.

I think every novice could benefit from these things:

1. Learning mating patterns.
- Chandler's "How To Beat Your Dad at Chess" is good.
- Renaud & Khan's "Art of Checkmate" is also good.

2. Being able to spot tactical motifs instantly.
- Winning Chess by Chernev & Reinfeld has 300+ exercises with some
verbal explanation.
- John Bain's Tactics workbook is recommended by many, but I don't think
it's a good value.
- Convekta's CT-ART is recommended by many. Lots of problems, good
value. I don't like the interface, but those who prefer to PCs to books
might have a different opinion.
- Reinfeld's 1001 Combos and 1001 Checkmates are probably the best
value. No words and old-style notation turn off some.
- Encyclopedia of Middlegames is good.
- I'd stay away from the Polgar book. Too many composed positions.

3. Recognizing threats.
- Dan Heisman wrote a book a couple of years ago on this topic.

Be warned: It is not enough to read these books once. I'd read one of the
mating pattern books and one of the combo books at least 3 times each.
Better still would be to read them so you recognize the patterns instantly.
This will take months -- possibly years.