The thing about verbal is that... its basically a reading comprehension test. The better of a reader you are, the more obvious the answer to the question will be. And I don't think its too late to start reading some hard material till test date actually(2-3 hours of reading economist a day and UNDERSTANDING whats going on will up your score at least 2 points I think in 20 days)
For example, If you compare an average reader with a good reader on reading a super convoluted verbal passage, the average reader will become flustered and lose confidence because he/she can't follow the flow of the writing and have no idea what a passage is about; in contrast, a good reader will read the same convoluted verbal passage knowing that 90% of the material is useless and only that 10% of the material is actually making a point about something. Its that 10% that will get you all 6/6 or 7/7 on the questions.
Before this summer I never read much... no reading intensive courses or anything. Took AAMC 3 before studying and got a 7 on verbal lol. So I forced myself to read ALOT..
My summer reading list: 2-3 hours everyday all summer
-How to read a book by Adler <-- this book made me a huge fan of reading "great books" ; randomly came across it in the library , lol almost like fate
-The Republic - Plato
-The Iliad
-The Odyssey
-Wealth of Nations
-Pride and Prejudice
-Sophie's world
-Various works by Leo Tolstoy
then... magazines such as economist, new yorker, american history, architecture... etc.
As for technique, keep yourself focused by "guessing" whats going to come next, such as the transition words that princeton and kaplan preach... moreover = more evidence for a prior argument, however = negative aspects of the proposal are coming up... etc. And subtle answers are almost always better than absolute answers that include words like ALL, EVERY, NONE ... etc.
And last but not least; once you are able to "laugh" at the reading material on verbal, you will be scoring much much higher lol. It sounds weird but there are actually a lot of subtle jokes/ironic points in our verbal passages... for instance in aamc 4 there was a passage about religion and how the followers totally 100% misinterpreted its meanings, half way thorough the passage I cracked up laughing thinking "these idiots are so stupid" lol, ended up getting all the questions right on that passage.
but anyways, good luck! I hope you do better