I sort of used ridiculously simple for micro, however toward the end I was running short on time and thus had to use First Aid. What I ended up doing and I recommend is:
1) Memorize First Aid as best you can
2) Do the following topics from ridiculously simple:
Staph
Strep
Gram neg. cocci
Rickketsia/Chlam.
Spirochetes
Virology
I did farely well on micro on my exam report.