It's impossible to tell you how well you are doing just by looking at % right or wrong on a paper document. Since the GMAT is adaptive, you don't have to score super high % to get a high score, you only have to continue to do well enough to boost yourself into the hardest questions.
That being said, a 50-60% hit rate is probably only good for the hardest of questions if you are going for a top score. I would recommend that you purchase a RC book, or specifically the 3 verbal books from
manhattan GMAT or all the other solide verbal books out there. Developing a strategy, and recognizing question types/how to address them, will definitely help boost your score. You need to work on strategy and knowledge before you just start powering away at practice problems.
Practice problems should be used to reinforce the concepts you've learned. Use an
error log with these questions to you can come back to them alter also, once you have a better strategy in place.
Good luck!