Get A Great First Layer! Original Prusa i3 MK2 Bed Level Correction

The following is my full calibration procedure for my Original Prusa i3 MK2 3D printer.  I'm posting it here because this question gets asked often and I don't want to re-type it again.  Here's my disclaimer.  The following may crash your printer.  If you use the information here, it's on you, not me.

If you are using the standard .4mm nozzle, I strongly advise printing your first layer at .2mm  and start with WHITE PLA because it is the most forgiving and easy to see.  The "0.20mm Normal" settings as packaged in the Prusa Slic3r should work great.

Read Prusa's 3D Printing Manual!  The calibration info beginning on page 15 is important to do first.  Also, look at the bottom of page 22 for a photo of how the first layer line should appear.

1. Write down all present settings as the new ones will likely be close. 
2. Clean the bed with acetone and don't put anything on it.  PLA will stick.
3. Reset live z and bed level correction to 0.
4. Run the full xyz calibration on the LCD panel.  Assuming x and y calibrate OK (your printer as-built is square), move to step 5.
5. Run the V2 calibration g code file that came with your printer over and over, adjusting live Z to be as good as possible. A more negative number moves the nozzle closer to the bed... so -.500 is closer than -.200.If your PINDA probe is set properly, your live z will be closer to -.500. You only have 1mm of adjustment here so if your number is more negative than -.850, I suggest resetting the PINDA closer to the bed and go back to step 3.
6. Download the 30mmx30mm calibration squares file and print it, adjusting live z to get all the squares as good as possible.
7. Using bed level correction on the LCD, adjust each square's setting about 20 microns at a time until all squares are as good as they can be.
8. If that is not good enough, reset the LCD bed level correction numbers to 0 and alter your starting gcode as shown below....obviously with your own settings.
   
   
   
   
   
   You can adjust +/- 50 microns under calibration>bed level correction on the LCD. OR you can adjust +/- 100 microns in the G80 line of your start g-code. You cannot do both and 100 microns is the limit. (Machine will report an error if you go more than 100) In Slic3r, the start g-code is in the "Printer Settings" tab under "Custom G-code"
   
   
   If you have not adjusted your G80 line, it should read: G80; mesh bed leveling
   
   
   My G80 line reads: G80 L-90 R-100 F100 B50; mesh bed leveling
   
   
   You MUST have a G80 line in your start g code. If you don't you WILL crash your nozzle into your bed!
   
   
   What mine "says" is move the nozzle 90 microns closer to the bed on the left side(L-90), 100 microns closer on the right side(R-100), 100 microns away from the bed on the front (F100), and 50 microns away on the back (B50). The baseline from where these moves are made comes from your live Z adjust position.
   
   
   Once dialed in, write down all your settings just in case they get deleted. If your bed is warped beyond this guide's scope, you may have mounting issues or require a new bed.