I thought I would share this since I have had a mini breakthrough with sentence correction. I have read through the Manhattan guide a few times, but it wasnt until I started taking notes on each section that I really began to understand some concepts that I "figured" that I knew well enough. This may seem like common sense to many of you, but going through the entire book line by line and rewriting and rewording the info. made me focus even more. So, if you are struggling a little bit or feel like you are not "getting" everything, try it.
Also, I am going through the Powerscore SC guide and although I think it goes a little overboard with definitions and such, I think it is worth the same exercise. The Powerscore book presents the info. in a different way and stresses some aspects that Man. does not, so I think both are worthwhile for a better SC score.