Paul Cunningham is one of the authors of the great Office 365 for IT Pros book which you should definitely buy. Recently released in its 4th edition the book is updated weekly as Office 365 changes. In addition to this book Paul also runs the Practical 365 community site (formally Exchange Server Pro), he is a Microsoft MVP, writes for Microsoft Press, and does courses online for Pluralsight. When it comes to Microsoft Exchange and Office 365, he is definitely an expert.
For this article, his selection of free scripts and tools available here are especially impressive. On that page, there are many scripts for Exchange Server, Office 365. Amazon Web Services, and general Microsoft platform PowerShell scripts that are free to download and use. We won’t repeat all the information on the page here but will call out the Exchange Analyzer tool that can query Exchange Server 2013/2016 installations and make recommendations based on best practice information. A free best practice consultancy session on Exchange servers.