Although I have not taken these exams yet myself, here is my advice on preparing for them, based on the numerous other exams I have taken and passed.
My general approach is to find a study book, work through it, and take practice exams, then go take the exam. The ExamRef books for these exams are:
Read the exam page on microsoft.com carefully – expand all the plusses.
Get the practice exam direct from MeasureUp – http://www.measureup.com/70-347-Enabling-Office-365-Services-P5550.aspx not from Mindhub.
Study carefully the concepts underlying every question you miss and every question you are not sure about.
Transcender doesn’t have them. SelfTestSoftware doesn’t. Those three vendors are the only legitimate choices I know of, so MeasureUp is your only choice. Be wary of other vendors – many are based on brain dumps, which are frowned up by Microsoft and can put your certification at risk.
In September 2017, I finally took and passed the 70-346 exam. Note that the exam was revised in June 2017. The exam ref book was revised too – look for the “second edition”. Make sure any practice tests you get are revised too – not all of them are!