I don't find on Internet Installation of Xamarin on Visual Studio 2017. Those who are looking for installation Guidelines this is for you

Step 1: First thing you must download Visual Studio 2017 (Community or Professional or Enterprise: For your Requirement).

Step 2: After downloading VS 2017, you have to run it then you’ll get this Screen :

Here we have Workloads, Individual Components and Language Packs.
Workloads: Go to Mobile & gaming at bottom Select Mobile Development with .Net
This is the Xamarin Workload for Visual Studio. You have So many Toolsets and Platform specific development workloads are there.
Optional:

• Add Asp.Net And Web Development – It will use for Services

• If you want to develop UWP application just add Universal Platform Development.
  (it will give sdk if you develop from xamarin.forms)
  Step 3: Individual Components:
  Next, you may see Individual Components section, there you must select latest versions of

• .Net Framework (Maintain latest to previous versions 2 or 3 (Because if you use solution from any other source. Example code from online they may used old versions) I have checked Most of the versions)

• Some Components automatically shows Tick Mark () because it will download along with the workloads we added in before section. So Don’t unmark those .
• In Development Activities: Select Xamarin Only no need of C++ and c++ android, iOS etc.
• Emulators: Google android Emulator (Sometimes it may fail to install). You can install it later If you got error.
• SDK’s and Libraries: Select Latest Versins for android and Windows SDK’s.
  Language Pack: You can select your well-known language for understanding. (Obviously English for me)

Step 4: Install it. (Its 20 to 29 GB Usually)
Getting Started Visual Studio Now:
Now login with Microsoft credentials if you have else create now.

Open Visual Studio and In File -New Project

Android native select android.
IOS Native Select IOS
Xamarin.Forms Selecet Cross Platform.

Now you can start developing Applications. Hope its useful for New developers.