Introduction

From this article, we will start with the Xamarin Android App Development Series. In this, we will learn how to setup Xamarin in Visual Studio.
Xamarin
As you know, Xamarin (http://xamarin.com/) is a cross-platform app development platform that enables you to create Android and iOS native apps using C# as a backend language.
Prerequisites
You need a good broadband connection before you start.
Note: Do them all, install all of them. And make sure your first install is the JDK and then the GTK for Windows. And the SDK and NDK are in Zip files so extract them in the same folder.
Procedures
Step 1
After installation and extraction, move to the folder where you have your Android NDK and SDK. Suppose I have the SDK and NDK in my C:\ drive.
Android NDK and SDK
Note: If you want to update your Android SDK, then you are free to do so. Go to adt-bundle-windows-xxxx > SDK Manager.exe.
Android SDK executable file
Just select your desired API and install that package. It's not mandatory, but if you experience any problem regarding the API or the API is not supported, then you need to.
Step 2
After installing the Visual Studio Xamarine Plugin, you have modified your Visual Studio to something like this:
Visual Studio Xamarine Plugin
Before creating your first project, please follow Step 3.
Step 3
Navigate to Tools > Options and you will get an Options Window.
Visual Studio munubar
And the Options Windows is as in the following:
Android NDK and SDK location
Now, you need to browse to the SDK and NDK folders in the Android SDK Location and Android NDK Location.
When you click on Change it will pop up a Browse For Folder as in the following:
change Android NDK and SDK location
That's why, I have suggested you put the SDK and NDK in same folder or a drive. After setting both of them, click on OK.
Step 4
We will now activate our Xamarine Trial account.
Tools > Xamarin Account
Xamarin Account
Register your free account and then, Login for 30 free days.
Step 5
We are now ready to start our App devolvement.
Go to "File" -> "New" -> "Project...".
App devolvement in Xamarin
Provide a name then start to develop.
Step 6
It's time to create an Android Emulator, just like your Windows Phone Emulator.
create an Android Emulator
Click on the button highlighted in Yellow and you will get something like this:
create a new devicet in Xamarin
And click on Create to create a new device.
start Emulator in Xamarin
And, okay then you have your device named here. To start your Emulator click on the Start button that is on the right pane.
Android virtual divice
Note: I recommend you use an Android device rather than an emulator since it is very slow and unresponsive when you work with it since it is less compatible with Visual Studio than Eclipse. (I say that from my personal experience.)
Execution
And if everything goes well then you may have this:
build Xamarin page
And the Android window is like:
start Xamarin android
Troubleshoot

Conclusion

It is a bit tedious to set up the Xamrin tools and add-ons in the right side. You are always prone to new errors. Use forums.xamarin.com or stackoverflow.com to correct it. Or, I can help you.