Follow the Steps Given Below

1. Project should be bug free.
2. Remove extra validation from Android tool
   1. Windows -> Preferences -> Android -> Lint Error Checking =>Ignore All
3. Create Key Store
   1. Right click on project -> Android tool -> Export Signed Application Package
   2. Select Project name
   3. Give location path where key will save.
   4. Enter Password as android and alias as androiddebugkey
   5. Enter details in the following image:
   6. Give release apk path:
4. Now APK is ready to place into Google play console.
5. If application uses some Google API like Map, then you need to do several steps more which are in the following way:
   1. Go to Windows -> Preference -> Android -> Build -> custom debug key Store -> Browse. You will get the following screen:
   2. Click on browse and select keystore file:
   3. Copy SHA1 fingerprint and Click on Ok. Replace SHA1 fingerprint with old one in Google API console.