Set specific reminders for yourself by asking specific things like, "Remind me tomorrow at 7:30am to bring my charger to work."
If you plug your iPhone into your car's sound system, you can tell Siri to play a specific song, artist, or album while keeping your eyes on the road.
When you have an app open on your iPad, simply hold down the Home button to bring up Siri and say, "Settings" to quickly navigate to that specific app's settings.
If Siri misunderstands you, just tap your speech bubble to make a correction