When using a laptop with Windows operating system to serve the needs of work, study or entertainment, you need to apply some energy-saving tips for long time use.
Reduce laptop screen brightness
You do this by going to the Power Options function in the Start search bar or in the Control Panel. Then lower the Screen brightness bar, like in Windows 10, go to Control Panel -> Hardware and Sound -> Power Options.

Note: This way you save the amount of battery that laptop is consuming. But looking at the screen is a bit uncomfortable when it's quite dark and in bright light environment is prone to glare.

Turn off connections when not in use
When not needed. You should turn off Wi-Fi, Bluetooth and USB connection on the device. If the laptop in use has a switch to turn off, then you just need to slide to turn off shortcut is finished. With Windows 10, most connections can be turned off in Action Center. For Windows 7, press Windows + X and then click the Turn Wireless off button to turn off Wi-Fi.

Note: There are many connections you can't turn off (for example), and turning off Bluetooth on Windows 7 is not very simple.

Turn off startup applications
Many software running with Windows makes the boot speed of the system slow and the machine running more, using more resources to run in the background.

You can turn off by: In Windows 7, press Windows + R, type msconfig and switch to the Startup tab, then uncheck the unused. It is recommended to remove only viruses, IDM (or other download managers) and Unikey, leaving the rest. When needed, you can still turn it on.

Decreased graphic effect
By reducing the effect, you help the laptop reduce the processing burden as well as RAM. Right-click My Computer (or This computer) and follow the picture below.