1. Don't download apps that use permissions you wouldn't give them
2. If you're using Android 4.3/4.4, look for 'App Ops' (The one that requires zero permissions) from the play store. It allows you to turn specific (though not all alas) permissions off per app: Notably SMS, reading contacts, keeping the phone on, polling your location, call log/making calls/clipboard/audio focus/camera/record audio/modifying system settings...
The benefit of Android's App Ops is that it also tells you when the app last used a given permission, which really tells you when some program has been exploiting your good will... Just remember though:
Whenever you have ads in an app, always expect
and maybe LOCATION_FINE
Pretty much all ad platform tools require them to function