Since we are only doing NAND consoles I'm not covering the other models.
Here's some tips to remember while taking apart your ps3:

• It's important to buy high quality thermal paste (I used arctic silver 5*), 70% isopropyl alchohol and paper towel before teardown.
  *[Warning] arctic silver 5 has a setting period of 60 hours before it makes a solid connection play games 2 hours at a time only
  It's also quite conductive so be extra careful not to get any on the board
• Store all the hardware in the ps3 lid to save space and avoid losing parts (see picture below)
• When applying thermal paste just apply an amount a bit smaller than the size of your pinky nail on the very center of the chip
• When placing the heatsink back on leave the fan off so you can align the heat spreaders properly
• You can avoid removing the warranty seal by forcing the lid off
  (push the top cover towards the side with the warranty seal until you hear an audible crack)
• You can also remove the warranty seal without damaging it using a heat gun and a razor

Here's videos describing the tear down and opening without voiding warranty: