Cultural differences between Mexico and USA #1

I think is fun and interesting learn something about cultures. When I came here to USa, I never imagined to sitting down with people from other countries. I am still quiet in the class, I don't want to offense anyone with my actions, but the people know hat i am kind of crazy.
First seven months I lived in California, I have cousins at there, even when they are hispanics, they have been raised with the culture from here, just couple ones have learned some of our real Mexican culture, and got some troubles, well, just people confused this, even I.
For example, In Mexico yout can say "hi" to anyone even though you don't know her/him. Or if one of your friends introduces to you other person, you can kiss him/her in the cheek. And when my cousin was introducing me with the other people, they just stare their eyes at me, I didn't know what to do, my cousing explains them later what it means. I feel unconfortable at this days so far, all my life I have been doing that expression, and probably when i back to Mexico i don't know how I will feel if I don't feel the same kissing to my friends in the cheek.
I have to say something. Man to man don't kiss them each other, we use to shake our hands or hit our hands with a punch. something that in here doesn't happen too, it probably means in here that i am being agressive.