I'm pretty sure you heard this saying "if you want to know somebody go on a trip with him/her". This is really true, I wonder why is that?
It might take years to know someone but traveling is like a shortcut . You learn a lot about your friends on a 10-day trip but you might not learn as much during a year of friendship.
You learn how flexible, tolerant, considerate your friends are. How much they can be easygoing? How selfish they might be to ignore you and act as they are on their own and you don't exist?
When you are going on a trip by yourself, you are free to do what ever you want (obviously) but when you are traveling with couple of people, it is very important to be cooperative. To be considerate enough to let everybody enjoy the trip. Try to learn about their needs and share yours to come up with the best solution for the entire group.
You need to listen and speak up both otherwise there is a good chance that you become (if you don't listen) pushi and boss your friends around all the time or (if you don't speak up) ends up being ignored all the time. Balance is everything.
This summer I had a chance to have short trips with different groups of my friends. I learn a lot about myself and them. Some of my findings are quite surprising :))