Disclaimer this guide is provided "as is". It's your guitar, so any work you underatake on it must be your responsibility. Make sure you understand the procedure fully before you start any work and please don't practice this type of thing on the pre-CBS Strat you found in the attic. The following thread uses a Squier Precision Bass to show the technique. The construction of this bass and the principles behind shimming the neck are exactly the same as for a Strat, it's just that I needed to carry out the procedure on this particular bass so I took a few photos. I'm not a luthier - just a keen amateur so feel free to add any comments or tips that might help others.