Whenever I'm in an environment with people I already know like school, I have no problem meeting new people and making new friends.

But it seems when I come into a totally new environment where I don't know anyone I become extremely shy, social hapless and tongue-tied.

This problem doesn't affect me much right now, but it sure as hell will when I goto college.

Any advice on dealing with this?

Let it happen, it's natural. It's basically you being really cautious, which is always a good idea in new environments and situations.