In each situation the occupation challenges fundamental property rights. In Australia the mini occupation is an under utilised tactic. People seem happier to be involved in vigils, pickets, rallies and demonstrations than occupations. I've been involved in four mini occupations over the past two months. On each occasion we were able to make our point with a small number of people and more importantly challenged institution's property rights.
Surprise is the most important element of any occupation.
If the institution who's property you are going to occupy gets a sniff of what's going on, all they have to do is put a few security guards on the door to stop you. As we all know possession is nine tenths of the law. A few hints for a successful mini occupation, move in as a group, make a circle once you're in, unfurl your banners or signs after you've gained entry. Start a meeting, ignore those around you, they'll be in a state of panic. They won't know what to do.