I took the Micro shelf a few weeks ago and did quite well (93rd percentile nationally.) What helped me the most was doing lots of practice questions. Levinson and Jawetz's Examination & Board Review had hundreds of questions and was VERY helpful. Most of the practice questions were divided up by subject (bacteriology, parasitology, virology, mycology, immunology)- so what I did was start by doing all the questions in a section. Then, I reviewed what I missed by looking it up and reading the relevant chapters (which are mercifully SHORT! Some chapters are just a page or two long!) There are also 2 comprehensive USMLE-style practice exams, which I took at the end for a final review. It's not as entertaining a book as Made Ridiculously Simple, but I personally found it more useful because of all the practice questions.
Another helpful option is if you're going to sign up for Qbank for boards review- go ahead and sign up now so you can do their micro and immuno questions for practice.