The most environmentally friendly way of travelling there is. Everyone who gives you a lift was already going that way.
But beware. Hitchhiking changes you. Your views on travel and where you can go change, and when you get older and have transport of your own, you cannot in all conscience fail to stop for anyone who needs a lift.

Better to travel hopefully than to arrive categorises the act of hitchhiking better than any other form of travel.
That is what you will tell yourself when you have been standing at the same junction for hours on end. So always hitch with a friend. It makes your trip safer, though usually a bit slower, and you always have someone to blame.

Hitchhiking does seem to be dying out except among people in the motor trade (They cheat by waving trade plates). This is such a shame.
If you have ever considered chancing your thumb, the best possible introduction to hitchhiking is the HHG to Europe by Ken Welsh.

Learn the uses of common objects while hitching (It's not just towels folks)

Be amazed by useful advice (from field researchers) on defrauding vending machines in neighbouring countries with similar sized coins.

Laugh when in the next edition someone complains because they tried it and got deported.