How to install a custom ROM on Samsung Galaxy S3 GT-I9300

The next step after rooting that you should go for is installing a custom ROM and finding the most convenient one.

There are many custom ROMs available on the internet which can be downloaded at any time.Custom ROM that you download should be exactly for that device which it is made for.

Copy the downloaded ROM(zip) File to the root folder of your phone.

DO NOT extract it.

Warning:- Installing custom ROMs can cause harm or may brick your device.Proceed at your own Risk

Put your phone in recovery mode by pressing home+volume up+power button and releasing it just after the samsung logo.

You can see your phone booted into recovery mode

Now Using your volume up and volume down to scroll and power button to select the option.

Select "Install Zip"

Now Select "Choose zip from/sdcard" and navigate to your ROM file that you've copied

Find your ROM file and select it.

Here we are using S5 Sensation ROM . But You may select your desired ROM.

Click "Yes - Install ROM"

You are Done !!

Proceed with the On screen instructions and you will have your custom ROM installed on your device. Reboot and Enjoy !!