Start Android SDK Setup.
JDK must be installed. Click Next.
Choose a location for the SDK. (Keep this in mind)
Now specify if you want to have a Start Menu Folder or not and click Install.
Wait until the installation has finished.
Now start the SDK Manager and download the SDKs you need.
Now choose Help > Install New Software.
Give it a custom name and this location: http://dl-ssl.google.com/android/eclipse/
See Installation Details and click Next.
Accept the terms of license agreement and select Finish.
Now wait while the Plugin is installing.
Now go ahead with Window > Preferences.
Choose Android on the left hand side. Insert your Android SDK location on your local machine (You have specified this before).
Have fun developing some Android Apps.