How to upgrade RAM for your Mac

One of my favourite lifehack blogs, Lifehacker, has posted this useful article on how to upgrade your brand new Mac's memory without having to sell your car to afford Apple's premium price.
If you're going to buy a new Mac I strongly suggest to take the smallest possible amount of memory and upgrade yourself following these great tutorials.
To be perfectly fair, always check your countries laws about warranties and the Mac warranty (or just ask any lawyer friend you have - and you definitely should have at least one) for some of these procedures may void your warranty in some cases (weird, but true...).