OG 12 is great, but I'm not sure if you need to do OG 10th. I suggest MGMAT Number Properties and Word Translations. I also suggest you review your incorrect questions and try to select the 5 or 6 skill tags that are your weakest and attack them systematically. Also, I'd suggest adopting a more stringent strategy for both PS and DS.
For example, this is how I approach DS:
A Process for Data Sufficiency
Step 1: Write down the Question Type. Data Sufficiency questions come in two forms. They either ask for a specific "value" or have a "yes/no" format. Determine which type of question it is, and write it down. Ask yourself: what kind of information will I need to answer the question? For "value" questions, a statement must provide a single numerical solution to be sufficient. For "yes/no" questions, either a firm "yes" or a firm "no" is acceptable but a single statement cannot be answered both ways. For "yes/no" questions, it doesn't matter how the question is answered, just that it can only be answered in one way.
Step 2. Write down what is NEEDED for sufficiency. Spend a few seconds brainstorming what kind of information would provide sufficiency before you move on to the Statements. What information do you need in order to answer "yes" or "no" definitiely, or to arrive at one possible value? It's okay if your prediction here is somewhat vague. Just get those wheels turnin'.
Step 3: Write down A B C D E or "12TEN" on your scratch paper. You will be eliminating as you go.
Step 4: Evaluate Statement 1. What information does this statement give you? For a "value" question, is it enough to determine a single value? For a "yes/no" question, does it answer the question in one way only? If the statement allows you to answer "sometimes yes and sometimes no," then it is NOT sufficient.
Step 5: Refresh the "Q" Before Moving on to "2." Re-read the question and reconsider the question type. Is it "value" or "yes/no"? What information would determine sufficiency? It's important to take this "breather" before reading Statement 2 to allow yourself to "forget" about the information in Statement 1.
Step 6: Evaluate Statement 2. Based on the question type, determine whether Statement 2 is sufficient. Does it allow you to answer either "yes" or "no" confidently? Does it give a single possible solution?
Step 7: Combine the Statements. At this step, the answer will be either C or E. Check to see if Statement 2 provides the information missing from Statement 1. What was lacking from Statement 1? Why was it not sufficient by itself? What information does Statement 2 provide?
I always write out my methods in shorthand and put it on my wall in front of the computer. That way, you always have something to fall back on for tougher questions. Good luck!
