Have proper sleep before a long day of wandering.
Do not let yourself go too hungry, else you get hangry (hungry+angry).
Have some snacks handy; food is fuel for the body.
If you get too tired and too hungry and transform into the evil travel buddy, pray your travel companions have the patience the length of the Great Wall of China, else they dump you in the middle of nowhere.
For more lessons from the road, please visit Go Learn.