- as superhuman says, keep that 2mm, nothing less because you will get pinch harmonics by accident, and nothing more because it's more difficult to brush the string with your thumb
- when you're accustomed with holding your plec like that, you hit the string and immediately after your plec hits the string, you turn your wrist a little bit outside making your thumb brush the string slightly making a pinch harmonic
- not all places sound just as good, so try to find your 'hotspots' on your guitar where you can get a nice pinch harmonic, the places are the same on each string
- to make the pinch harmonic really squeel you use vibrato a lot or simply bend it, also using your whammy bar can sometimes make one hell of a sound
- the more distortion/overdrive, the better you'll hear your pinch harmonic
- each guitar gives a different sound, so if you can practise on other guitars please do
- practise a lot! being able to make a pinch harmonic is one thing, but being able to do one during a song is way more difficult
- good luck! :)
= good music is good drinking =