1) Install the latest version of Unity
(https://unity3d.com/), check during the installation process: ‘Microsoft Visual Studio Tools for Unity’

2) Install the latest versione of Visual Studio Community, with C# support enabled
(https://www.visualstudio.com/vs/game-development/#tab-4b0d0be8de5f65564ad)

3) Open Visual Studio> File> New> Project> Game> Install Unity> selezionare ‘Visual Studio Tools for Unity’

DONE!

Open Unity Editor, you will find:
Top Menu> Edit> Preferences>External Tools> External Script Editor> Visual Studio 2015

Select a C# script, open it and Visual Studio will start automatically.

Visual Studio is more solid than Monodevelop.

Inside Visual studio you will have:

– main window with a good autocomplete code tools
– main window with mouse hover description of commands
– main window with locked debug controllers, click in the grey vertical bar to put a debug stop point
– on the bottom an Output console
– on the bottom an Error List and tips about obsolete code
– on the right a pro class/functions visualization tool, check ‘Show All Files’ to see the same content of Unity> Project window

Reference:
– https://www.youtube.com/watch?v=2PVPz8Pnnrw
– https://www.youtube.com/watch?v=TPGp770JyDg