Hitchhiking is often a necessary aspect of a successful long distance hike. Whether getting into town for a resupply or its your preferred method of getting back home, hitchhiking can be a bit intimidating. However, if you can pull it off, it may also be one of the more exciting adventures of your trip. A phrase I heard often used on the Appalachian Trail is "There's no adventure on the white blaze". This phrase references the difficult monotony that often plagues long distance hikers and how very often, a hikers greatest stories come from off the trail such as in town or hitching to get there. This being so, it's important to know the do's and the absolutely do not's of hitchhiking so you're well prepared for your next long hike.
Hitchhiking isn't legal everywhere. It poses obvious safety concerns for both hikers and vehicles as it requires a hiker to stand in the often narrow shoulder of fast moving highways or winding roads with low visibility. It's discouraged in many places and is in fact criminalized in the following states: New York, Nevada, New Jersey, Pennsylvania, Utah and Wyoming. There have been roughly 500 interstate murders since 1979 which is still proportionally low in fact, you have a 0.0000089% chance of being killed or raped while hitchhiking.
Luck is your greatest chance of being picked up on the road. However, there are certainly many ways to better your chances. The first being to travel together, particularly with a female in the group. One lone hiker is more intimidating to many drivers than a pair or a trio of them. Having a woman in the group also makes you less threatening to passing drivers. It's important not to have too many people, however, as drivers probably won't have the space for everyone, along with their packs.
The appearance of those in your group is equally important to the size of it. Because of movies and stories popularizing and exaggerating the number of murders committed by hitchhikers, many drivers are already weary of you so try your very best not to look like a murderer. Some ways to do that include not wearing a hat, putting away any knives or stakes you might be carrying, and wear clothes of a more expensive brand if you have them (Patagonia, Sorel, Marmot, Under Armour etc). Keeping a beard well trimmed may also help.
Another tip to improve chances of success is to make your pack seem as small as possible so that passing drivers who might want to help, don't reject you due to pack size and their car's limited capacity. For example, anything you normally carry externally on your pack, move to the inside or get rid of it. For me, that meant moving my camp shoes to the inside of my pack and losing 2 empty water bottles I had been carrying. I collapsed my trekking poles as far as I could and wore as many of the clothes in my pack as I could comfortably walk in so as to reduce the size of my pack. This helped significantly in one of my ventures. When all our gear was where it had previously been, we walked for about 45 minutes on the highway with no luck, but as soon as we followed these steps, we were picked up in less than 5 minutes.
Consider making a sign, particularly one thats humorous. This humanizes you and says that you're not a voiceless vagabond in need of charity (although you very well may be). Something like "AT thru hiker- Need Ride -Does not bite" or "Hiker in need of ride. Snacks appreciated". It also may be advantageous to state mileage unless you need to go over 10 miles.
The place at which you hitchhike is very important as well. Some roads may be more difficult or more dangerous than others. Its best to position yourself on a straight stretch of road with a wide shoulder so you're visible to vehicles from a greater distance and they have room to pull over when picking you up. Avoid hitchhiking at night and if possible, hitch on roads with a speed limit no greater than 45 miles per hour so that stopping time for vehicles is reduced. It is very difficult to get rides on highways and nearly impossible on interstates due to a combination of high speed driving and increased traffic. On roads with a lot of traffic, you'll find drivers are less likely to help simply because they expect that if they don't, someone else will. This diffusion of responsibility means that then no one offers their help.
These tips may help you find a ride but of course in the end it comes down to the kindness of a stranger and unfortunately such kindness is never guaranteed. So when you do get picked up, be sure to be grateful and polite and do your best to make a friend. Thats what adventures are all about. Experiencing new things and meeting new and interesting people.