I am getting ready to begin studying for the SCJP 1.6 with the Sierra Bates study guide. I was also planning on completing the JavaRanch Cattledrive at the same time as another way to prepare for the exam. I would love some feedback as to whether or not this is recommended, or should I just focus on the study guide.
The SCJP/OCP-JP is for experienced programmers. So getting as much hands-on is highly recommended. It doesn't matter if it's Cattle Drive or exercises from text books/study guide or simply testing the concepts.
The most important thing about studying is understanding why such and such is correct/incorrect. Reinforcing this with hands-on examples will help you remember more.