Christina_

I took the NCLEX and passed 75 questions. I only used UWorld. My scores in UWorld ranged anywhere from the 50s-the 80s. I focused on systems rather than mixing them because that is what I prefer. Some people may like mixing the questions instead. I did the whole Qbank and answered 50-100 questions daily. But everyone is different; I had friends who only did 100-200 questions from UWorld and passed. Everyone is different. The best thing you can do to prepare for the NCLEX is practice questions, but don't overdo it. Give yourself a break and have time to relax. I bought UWorld in May, but I started using it in June, so I used it for a month before I took NCLEX.
The best advice I can give you is to read the rationale for every question. Even the ones you got right, just read the explanation. And for the ones you got wrong, understand why it was wrong.