Ultimate battery saving guide

Smartphones have come a long way, today we have phones are more RAM than desktop computers few years ago. Smartphone displays  have become bigger, brighter & now have more resolution than you'll ever need. So much resources needs for too much power which unfortunately many OEMs don't focus on and you end up with empty battery in the middle of the day.

Now battery life depends and varies on usage so after using these specs too you won't get an hour extra of candy crush. But it will sure provide with some better standby time. And slight increase in   SOT too*

I will divide this post in two parts - basic and advanced

BASIC
(Most of this is obvious stuff but it works and and are useful for a basic user)

1. turn off location sharing. This uses your data to send location information to figure out your location in background

2. Enable dark theme in apps where ever applicable & use dark/black theme if available (works for AMOLED displays)

3. Use phone with as much less brightness as you can. Turn off auto brightness.

4. Don't use resource heavy apps / games if you're no where near a charger (no brainer)

5. Turn on battery saver mode if your phone has. With lollipop, android introduced battery saver which under clocks your CPU, reduces screen brightness, and disables animations. Use ultra power saving modes (available in some Samsung phones)

6. Uninstall unused applications or disable unused system apps (which can't be uninstalled). These run in background and use your battery.

7. Turn off mobile data and or WiFi & Bluetooth. Also you can turn on Airplane mode to reduce power used by network radio.

8. Use a 2Amp charger or quick charge enabled charger if your phone supports it (use at your own risk / don't use a 2 ampere charger if your old devices rated for less than 700mA). You can also carry a powerbank which range from 5000mAh to 100000mAh

ADVANCED

(These steps need you to root your phone. Use these steps at your own risk. Unlocking your bootloader your phone will void your warranty. I am not responsible for the damage caused by these steps. However you can ask any questions regarding these steps)

1. Install greenify. This is the first app every user who roots should have. It disables apps running in the background

2. Enable aggressive doze mode in greenify which reduces the time in which your phone goes into doze

3. Install kernel manager and most kernels allows you to set brightness below the default set level. Gravity box also has that option but kernal manager also gives you other useful options too.

4. Underclock your CPU in kernel manager. Or use power saving governor if you're not sure which values to put.

5. You can try undervolting too but it's riskier than underclocking and is recommended only for 'very advanced users' and may break the device.

6. I am not recommending to reduce your resolution to a lower one because it doesn't makes any significant difference. However you may reduce your DPI for cosmetic purposes

7. Uninstall unused system apps. Most of us don't use apps like slides, sheets etc and other system apps but you can't uninstall them normally but you can using many uninstall managers which needs root. Uninstalling these apps not only reduces stress on phone but also gives you more storage.

That's pretty much i do for getting most out of my original Nexus 5. I get around 4 hours of screen on time and a day worth of standby.
-stock ROM
-franco kernel
-using 2Amp charger
But that's with normal usage of watching some YouTube videos and listening to music, and make calls, type some documents & chat a lot. Your results will vary greatly on the apps you use.

If you have another apps/tips you use feel free to share them in comments