There's a method to playing pinch harmonics, although it's easier to show it than to explain it. But here goes, anyway - first, make sure you hold your pick pretty low down, with just the tip protruding (like, just 3 or 4mm). Then, just after picking the note, let the edge of your thumb sort of just only very barely touch the string as your hand moves past it. It helps to bend the string a bit, and I've found that pinch harmonics are easiest to pop off the G and B strings. The trick here is not to think about it, because if you do, you'll try too hard to brush your thumb on the string and it won't work. :P If you ever play regular harmonics (ringing off a note on the 12th fret, for example), you'll know what a light touch is needed. It's the same for pinch harmonics.
This video is quite long, but it shows you
exactly how to do it properly.
I was in my first band in grade 9. It was pretty grotty, and we only ever played one proper gig and it was barely a proper gig at that, heh. I was in another two bands during high school, and played quite a lot more gigs around town, but nothing special. Then when I was doing my postgrad, I joined a band a bunch of friends were starting up, and that lasted about 2 years or so. At the height of that, we were playing around Cape Town almost every weekend and sometimes during the week too, most often at Cool Runnings and the Armchair Theatre in Observatory, and the Mercury (up- and downstairs). We were actually kinda popular for a while, but after I graduated I went off to America for three months and we just never managed to get stuff going again when I got back. Kind of a pity, I suppose, but it wasn't
quite the sort of stuff I really wanted to be playing, anyway. It was loads of fun, though.