If you don’t need them, disable Wi-Fi, Bluetooth, and GPS. Go to your main settings and turn them off.
This is as simple as simple can be, but I’ve found this can save you a lot of power. It’s also handy to turn these off when you can’t reach one or the other of these services. That’s because, otherwise, they’ll keep trying to connect — and that eats up an amazing amount of battery. For example, I primarily use Bluetooth in my car. If I leave Bluetooth on when I’m not driving, I lose an average of 30 minutes a charge. That’s a big deal.