As i have mentioned the key here is to understand the basics and have good foundation of fundamentals. You should go through all the concepts tested on the GMAT. You may purchase all the quant books from Manhattan and go through each and every one of them . Also make sure you sre practising lot of questions. For practice, you may initially refer OG,PR and kaplan
. Once you hit 40+, then you can go for club challenges.
You will require time for this and be prepared for hard work for at least a month or two on quant. If you have any specific questions on particular topic then post it here, you will get loads of explainations.
Again, i want to reiterate that, for quant, there is no substitue for loads of practice. Good luck.