I hang out on the Lonely Planet forums a lot, and there's an incredible amount of interest shown towards tips and tricks for being a 'person of distributed household' -- homeless, vagrant, what have you. As I've had a bit of experience with this, I wrote a piece for a fellow travel enthusiast to post on his blog. I shall reproduce this, abbreviated a bit, below.
I had the interesting challenge over the summer of having to alter my comfortable routine of living in the wilderness to suit the environment of southern England, which is bustling and very densely-populated. After finishing my first year at university in Scotland, the only thing for me to do was to explore the fabled Highlands. This I did for four glorious weeks, living deliberately and all that.I had to be at a wedding in Oxford two weeks from when I finished, though. I didn't want to spend £100 on a train, so I formed the plan of hitchhiking all the way, tenting it where I could, and hoping my outdoor skills would still be of use in the modernized towns and farmland.
First, a bit about the basic mechanics of hitching in the UK. I found that the further south I got, the longer I'd have to wait. Also with towns closer together the rides are usually shorter. What I resorted to was the ol' whiteboard routine, standing outside rest stops along A-roads. Unfortunately this tends to get you into big cities; I narrowly avoided getting plunked off in the middle of Glasgow, but I hit Birmingham dead-on, and it's not the kind of place you'd want to leave your thumb exposed.
I'd gotten a bit spoiled in Scotland, which has passed revolutionary laws regarding camping. You can pitch a tent almost anywhere as long as you don't frighten livestock. I was shouted at once by some early-morning golfers whose putting green I had infested, but if that's the only thing that annoys a Scot, well God bless them. In England, however, this is not the case. "In England we're too lazy to come up the hill and tell you to feck off" I was told by one aged man, and of course you're not going to get fined or arested if you kip in a cornfield. The only thing is, it's hard to be subtle when unused land simply doesn't exist. Ultimately my advice regarding this: don't be as paranoid as I was; get comfortable and leave if somebody asks you. Happily, there are very few midges down south.
Hygene is obviously extremely important when hitchhiking. If there's a small, flowing stream, I'm happy to bathe in it or do laundry; the colder it is, the more of a mountain man one feels. I use Dr Bronner's castille soap, which is biodegradable and is perfect for camping -- being highly concentrated you don't have to carry much. Half a teaspoon was enough to wash my mop of hair. When it came to the city I figured that I wouldn't care if I walked into a public bathroom to find some guy washing his hair, so nobody else would either.
There are many reasons I'm glad I hitched. foremost of these is that If I'd taken a bus or train I wouldn't have ended up in the Lakes District. I'd been lucky enough to be picked up by a man who was attempting to climb the three highest mountains in Britain in one day, and was trying to make record time between Ben Nevis and Scafell Pike. He balanced out the man who took me from Manchester to Birmingham, going 50 mph and playing some kind of truly horrific tribal music while I was ill and hadn't slept. Good or bad, every driver contributed something to my journey. I engaged with many others as well in ways I never had before. After a rainstorm I went to a church service just to warm up, and ended up spending the day at the house of the minister, reading Calvinist pamphlets and dining heartily. A fat woman whom I had been mentally abusing for taking up a whole bench walked up and handed me £15 and a pasty, saying "Jesus loves you."
After my rather rough immersion into vagabond life among the civilized, I still feel a bit of a greenhorn, but with the pervasiveness of urban society I witnessed over those months, only knowing how to live in the wilderness is clearly not enough. Life on the streets can be extremely taxing, and knowing how to handle it is therefore an immensely valuable skill for a young person to acquire.