Thank you Pooja.
Which edition of Manhattan SC do you have? If you have the 2003 edition, then I suggest you get the latest edition. Buying the book will also give access to MGMATs.
OGs and the Manhattan SC guide are your best SC resource.
You can skip OG11 and do OG12 and OG10 instead. Do the SC sections in each OG a couple of times and go thru the explanations. You should not only analyze your mistakes and see where you went wrong, but also go thru the explanations of the questions you answered correctly and see if you eliminated the wrong choices for the right reasons. I did my OGs 2-3 times, and learnt something new everytime.
My advice would be to go thru' the SC guide and OGs as many times as possible. Make your own notes about the new rules or idioms that you might come across.
You could also buy the Verbal Review for the Official Guide 2nd edition for extra practice.
I would not recommend the 1000SC 'cos some of the questions are very poor standard and some of the answers given in the document are wrong. Although, they contain a lot of practice questions, you are better off sticking to the OGs. Another thing is that most of the questions in 1000SC are from OGs and GMATprep softwares. So you'll end up seeing a lot of repeat questions.
Practice from good sources is the only way to improve your speed and accuracy in SC. I was exactly where you are right now (in terms of verbal performance) when I started preparing. I did a whole lot of SC's and going into the GMAT SC was one of my strongest areas. If I can, then so can you
I hope that answers your question