A huge problem in amateur (and sometimes professional) photography, is knowing what you are, and aren’t allowed to photograph. Are you allowed to take pictures of that building and if a security guard demands you delete that photo, legally, do you have to?
Photojojo have given some tips on some of the laws of photography. I believe these are the american laws, but many of them are the same as in the U.
http://photojojo.com/content/tips/legal-rights-of-photographers/