Yes, I joined Java Ranch on the day I cracked OCA. And God knows how I cracked it! I need some valuable suggestions guys, so read on:
I read OCA topics from Head First Java book, except the chapters- Object Lifecycle and Statics in a month. I was also enrolled in Java training course at my college, which did help but in a really marginal way.
So I was pretty clear in concepts discussed in the first 11 chapters (except chapter 9 and 10 as told) of Head First Java due to which (maybe) I was able to crack the exam.
I didn't practice much writing code but covered all these concepts and when in doubt used Stack Overflow.
I don't know whether it was good luck on my side that I was able to crack the exam but all I know I want to review these OCA topics again. Should I NOW buy Sierra/Bates cert guide to revise all these topics? Or considering my placements going on, should I focus on just Head First Java and implement Data Structures in Java?
If you pass OCA7 and want to get OCJP - K&B is best book i read (for OCJP7).
In preparation of oca i prefer Mala Gupta`s book, but for OCJP - K&B is the best.
Also great material for OCJP is JLS and Angelika Langer generic FAQ
If you not interesting for OCJP just read book for specialization you choose.