First, there is no single "best" way to study for exams. Not everybody learns the same way, and so different study methods work better for different people.
Secondly, certification is not about learning. Certification is a validation of the learning and experience that you already have. If you have worked with the product and have real-life experience then you should be able to pass the exam by doing a couple of reviews and practice exams, and then following up on areas where you are weaker.
Thirdly, TestKing is terrible. They don't provide questions that are "exactly like on the exam" questions. They provide actual questions taken directly from the exams that have been obtained through illegal means. They are also considered cheating by MS Learning, and while the chance of being caught using TestKing is slim the penalty for being caught cheating on an MS exam is a lifetime ban from Microsoft certification. If certification is in any way important to your career then you wouldn't cheat on an exam, no matter how unlikely you are to be caught.
Beyond that, TestKing produces "paper" certifications. People who use TestKing to pass an exam have only demonstrated that they know how to cheat on an exam. It doesn't mean that they have any ability or knowledge of the topics covered on the exam.
I had an associate who went to an MCSE boot camp once where all they did was memorize TestKing content for 12+ hours a day for two weeks. Everyone who went to the boot camp came out of it with an MCSE. Many of the people from the boot camp got perfect scores on the exams. Most of them had no IT experience whatsoever before coming to the boot camp, and had no more IT experience when they left than what they came with. What do you think happened when (if) they actually managed to get a job that required an MCSE? Do you think that they managed to not get fired for being incompetent? And how do you think that reflected on the MCSE brand in general when they did get fired?
Here's the next problem with TestKing: because they produce "paper MCSEs" who have no real skill, knowledge, or experience they devalue the MCSE certification. There was once a time when the MCSE was a highly valued certification and the average MCSE was making close to $95,000 a year. These days the average MCSE probably earns more like $55,000 a year, and you frequently see positions posted for helpdesk technicians where they ask for MCSE certification. The value of the MCSE has dropped precipitously because now there is so much more "chaff" mixed in with the "wheat" and companies cannot depend on an MCSE certification as a way to judge a candidate's skill level. If a certification is in any way important to you or your career, why would you devalue that certification by cheating to get it?
The real world isn't about regurgitating facts from memory, it's about problem identification, knowing where to find the answer, and knowing what to do with it once you have it.
While that may be what real world IT work is about, that is not what certification is about. Certification is about validating the skills and experience that you have with a particular technology. If you are not interested in validating the skills and experience that you already have then why would you bother getting certified at all?
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CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCSE:Security 2003
MCITP:Enterprise Administrator