Reduce screen brightness: Go to Settings > Display > Brightness, or use the brightness slider in the Quick panel;
Enable Power saving mode in the Quick panel when battery is low;
Close unused background apps (swipe up from the bottom, drag app cards up);
Turn off Bluetooth/Location Services when not in use (Settings > Bluetooth/Location or from Quick panel);
Avoid using the tablet in extreme temperatures (0°C to 35°C is the optimal range) — high heat reduces battery life.