About five years ago I was walking a dirt road between an old field to my right and pine/oak woods to my left when I spotted a six-foot beast of a black rat snake (Pantherophis obsoleta) exploring the fallen half of a split cherry tree. I clumsily detained it for a couple photos, and then I let it go. It headed for the standing trunk of the cherry and then flowed up about fifteen feet with absolutely no regard for gravity. It is the most beautiful thing I've ever seen a snake do. I recall another rat snake anchored in a cliff-face crevice on a mountainside in the Pocono Mountains and soaking up the morning sun before a day of hunting birds and chipmunks, yet another a patterned hatchling crossing a sand road in the New Jersey Pine Barrens at dusk.
Each of these was not simply a beautiful snake; it was a rich experience of a beautiful creature in a setting it evolved to master. This is why I go herping. Black rat snakes are beautiful snakes in any setting, captive or wild, and as arboreal constrictors I find them especially fun to handle; they're comfortable off the ground and they grip you back, what I think of as the rat snake handshake. But however much I love them in whatever setting, I'll take them in the wild if I have any choice in the matter.
I should make clear I also keep reptiles (five snakes at the latest count, and a history of innumerable other snakes, turtles, and lizards), but the thrill of finding the creature in its habitat (the red back salamander - Plethodon cinereus - under its damp log, the fence lizard - Sceloporus undulatus - darting off its stump, the spring peepers - Pseudacris crucifer - singing their tiny hearts out on a drizzly spring evening) keeps me out and searching, spending much more time slogging through marshes and peeking under rocks than cleaning cages.
I should also make clear that I don't limit my herping to grand, majestic terrain; I spend a lot of time in old cemeteries, vacant lots, and marshes with fine views of the Philadelphia sky line. I particularly like finding brown snakes (Storeria dekayi), little slug and worm eaters common in urban and suburban gardens and spotting turtles in the Schuylkill River, which flows through Philadelphia.
Interested in finding your own wild reptiles and amphibians? Start by reading field guides and basic natural histories. You can learn a lot online about how to find your local herpetefauna. Forums like Field Herp Forum are a great place to start, with herpers from all over the world (including the UK) posting their finds and the stories behind their successes. Be warned that herpers can be a bit anti-social compared to keepers. We spend a lot of time worrying that poachers or clumsy herpers will ruin our favorite spots, so you’ll have more luck asking for general advice rather than for directions to specific populations. It's also worth checking your local wildlife regulations before you head out. Few governments ban taking notes and photographs, but it's best to learn the rules ahead of time to avoid any sticky misunderstandings.
Calling it 'herping' perhaps implies more of a coherent discipline than it is; a lot of herping is just walking around and studying the ground. The more time you spend out searching in habitat, the better you’ll learn the patterns of the critters you hunt. Add in some basic techniques such as looking under rocks, logs, or human-made cover (always put any object back how you found it, THEN release the critter) or paying special attention to south-facing slopes on sunny mornings, and you can find enough to make it interesting.
He may call himself an amateur, but Bernard Brown is a master herper in Philadelphia, Pennsylvania looking for his favorite reptiles and amphibians. Still, he has no special training in biology. Nevertheless, his passion (or "obsession" as he likes to call it) overrides all. Catch all his herpetile adventures on his blog Philly Herping.