Previous experience: About six months of programming in college, then about 3/4 months of Java/Android in college.
Then about a month after I last looked at Java I dived into Enthuware`s practice exams and got 40%.
I then (part-time - while looking for Job) read the first ten chapters or so of "Deital How to Program" (not strictly necessary but nice to do) and then read the Sierra and Bates Certification guidebook (Chapters 1-5 - but not Wrappers/Boxing or Assertions - and added String/Stringbuilder, equals/hashcode and ArrayList stuff).
My enthuware scores:
Dates are formatted as DD/MM/YYYY for all you Americans who write the date backward!!
Mock 1 -- 24/12/2013___40% (77% Pass Rate - Jumped in with no preparation)
Mock 2 -- 04/02/2014___58% (77% Pass Rate)
Mock 3 -- 12/02/2014___50% (63% Pass Rate from here onwards)
Mock 4 -- 15/02/2014___53%
Mock 5 -- 16/02/2014___56% (Did not do "too difficult" or "Drag/Drop" Q`s)
Last Day -16/02/2014___62%
The exam itself was harder than I expected, but still easier than the Enthuware practice exams.