The dinky little light bulbs in most fridges don’t work that well - they tend to light up only one half of one shelf and that’s it. So I got bored and fixed this in my fridge by putting LED strip down both sides… Never again will I have trouble finding something in there. 
Because this potentially involves working with 240V I don’t want to encourage people to do this themselves with a step-by-step guide. If you’re halfway competent, I’m sure you can figure out how it works. 
BUT if you decide to ignore my safety advice and feel like doing something similar, here’s a few tips:
-Waterproof EVERYTHING. Don’t just use epoxy-coated LED strip and think you’re good - every single component needs to be waterproof, including your connectors. If you’re not comfortable dunking your whole thing underwater, don’t bother putting it in your fridge. Condensation can and will happen and that will make things go zappy zappy.
-Tap into the fridge’s light circuit since that has a handy automatic switch to turn the lights on when the door opens, and the stock light bulbs are often 25W bulbs so the wires can take the load of LED strip. Check the voltage of this circuit before you start as some use 12V bulbs but most use 240V. You may or may not need a power supply too.
-Try to do it non-destructively if you can, because being without a working fridge sucks. I’ve never liked wire taps so I opted to solder wires into a lightbulb converter socket so the whole thing is completely removable.
-Dry off the fridge’s interior panels using a hair dryer. This will heat it up & remove the condensation so things will stick to it. Don’t drill into anything because you don’t know where the refrigerant lines run behind the panels.
-Appearances matter. White electrical tape is awesome to make the wires disappear. Warm white LEDs will make your food look more vibrant, fresh & inviting than cold white.