Ahhh the $64k question!
Well IMHO Spotting is different things to different people.
Some people take along nothing more than a pair of binoculars and a notebook, taking down registration numbers of all the aircraft they've seen.
Others take it a stage further and buy scanners to listen in on radio traffic and maybe even a computer programme dedicated to logging all the aircraft movements data.
Others do it differently, and carry with them cameras to capture the image of the aircraft, either in flight (Approach and take-off) or on the ground (Taxiing and at the stand).
And then there's the really dedicated bunch who do all of the above!
Personally I'm in love with flight in general, and if I do go to an airport it's with a Camera with a big zoom and several rolls of film. I simply take pictures of aircraft. For me, the history of the aircraft, or it's registration or where it's just come from (or going) have no real interest, I just want to capture the image, and try to make it as good as possible. If they're good enough I will try to upload them to this site.
There's no such thing as the typical spotter... in fact I probably don't even qualify as a spotter by my own criteria, so let's just say I'm an 'Aviation Enthusiast'!
Hope that helps,
Flightlineimages DOT Com Photographer & Web Editor. RR Turbines Specialist