Start by checking the battery usage page to see which apps and activities consume the most energy. Bright screens, long video sessions, navigation, games, and weak cellular coverage can all shorten runtime. If one app uses unusually high power while you are not actively using it, review its background access, update it, or remove it if unnecessary. A recent software update may also trigger temporary background work.
Reduce screen brightness to a comfortable level and shorten the time before the display turns off. Use dark mode if you prefer it and your phone's screen technology makes it helpful. Turn off connectivity features you are not using, but do not disable useful services automatically; the savings depend on the device and situation. When reception is poor and you do not need mobile service, airplane mode can prevent the phone from continually searching for a signal.
Battery-saving mode can extend runtime by limiting background activity, sync, or visual effects. Enable it when you need extra time away from a charger, and review which functions it changes. If the phone still drains quickly despite modest use, check battery condition and installed apps, then consider professional service if the battery is worn. Consistent habits are more useful than extreme settings that make the phone frustrating to use.