The advice above pretty much covers everything, but to reword for benefit of others who will ask the same thing: Flashing an image is one thing. Creating settings/plugin backups is another thing. Restoring settings/plugin backups is yet another thing.
Create a settings backup: (this is with regards to those on your current image)
If you intend to flash by USB, you will have to manually create a settings backup
When you flash by Image Manager
or perform a software update, the default is to create a settings backup.
Flash an image
You can using a USB flash drive. Some people like doing things the hard way.
You can flash using Image Manager. This is the simplest thing to do. You also get the option of selecting which slot to flash onto for receivers with hardware multiboot
Restoring settings backup:
After you have flashed an Image, you will be asked if you want to restore the settings backups and plugins you had installed. Say yes unless you want to manually set things.
Note: CrossEPG is not pre-installed in 5.3 images. So you will have to manually install that.
Guide and videos on link below (as well as my signature). Also covered in the ViX manual
https://www.world-of-satellite.com/showthread.php?47588-Flashing-Settings-backup-and-Restores/
updating 
