Calibrating a Prusa i3

Hopefully you're reading this before you scratch the shit out of your buildplate.

• Level your X-carriage using a clinometer (free Android app, Clinometer) to level out the thing properly. You *could* use a bubble level, but those aren't accurate or precise enough.  
• Always make sure to
• Remove your phone case.
• Calibrate the clinometer app.
• Rotate the phone 180 degrees to mitigate the zeroing error that is inevitably leftover even after you've calibrated your phone. The object in question is actually level when you have the same reading after rotating the phone 180 degrees.
• Level out your buildplate.
• If you have a spring loaded assembly, which you should, you'll need to adjust the bolts in each corner. Follow this tutorial for further information.
• Want to hack your own springloaded assembly, but can't find the springs anywhere? Use the springs out of a set of the SAME unused clicky pens. You want the spring coefficients to all match up.
• Locknuts are your friend with these spring loaded assemblies, especially if you don't want to have to level out your buildplate every single print.
• If you have a fixed bolt assembly, you'll need to add/remove washers/spacers until the bed is level. 
• Calibrate your endstops.
• Z-stop: you'll need to bring the nozzle of the hotend down such that it is close enough to the bed such that you can run a sheet of paper under it. The paper should be snug; you want some drag on it. Then you will need to screw and unscrew the Z-stop bolt until you hear the telltale "click" of the endstop. Screw and unscrew it until you get that bolt as close as possible to the exact moment you hear the click when going down.
• Check your filament situation
• Make sure the hobbed bolt is clean and free of dust and debris.
• Don't forget to add filament.
• Check your wires, make sure nothing came undone while moving the printer around.