1. Confirm that your computer meets the System Requirements.
2. Download and install eclipse ide classic.
3. Download the Android SDK Package.
4. Install the ADT Plugin for Eclipse. You can find here a step-by-step installation guide.
After restarting your eclipse, a window will be shown up asking you to install sdk platform tools and others. Select the second choice to use existing sdk and browse to your installed sdk folder. for ex. D:UsersUser NameAppDataLocalAndroidandroid-sdk and move to step 5 to install sdks and tools.
5. Add Platforms and Other Components.
From within Eclipse, by selecting Window > Android SDK and AVD Manager, you can download SDK components into your development environment.